FAA-H-8083-3B Airplane Flying Handbook, 2016

• Operate the engine in such a manner as to avoid a extension. The pump that pressurizes the fluid in the system further over-boost condition can be either engine driven or electrically powered. If an electrically-powered pump is used to pressurize the fluid, the Low Manifold Pressure system is referred to as an electrohydraulic system. The system Although this condition may be caused by a minor fault, also incorporates a hydraulic reservoir to contain excess fluid it is quite possible that a serious exhaust leak has occurred and to provide a means of determining system fluid level. creating a potentially hazardous situation: Regardless of its power source, the hydraulic pump is • Shut down the engine in accordance with the designed to operate within a specific range. When a sensor recommended engine failure procedures, unless a detects excessive pressure, a relief valve within the pump greater emergency exists that warrants continued opens, and hydraulic pressure is routed back to the reservoir. engine operation. Another type of relief valve prevents excessive pressure that may result from thermal expansion. Hydraulic pressure is • If continuing to operate the engine, use the lowest also regulated by limit switches. Each gear has two limits power setting demanded by the situation and land as switches—one dedicated to extension and one dedicated to soon as practicable. retraction. These switches de-energize the hydraulic pump after the landing gear has completed its gear cycle. In the It is very important to ensure that corrective maintenance is event of limit switch failure, a backup pressure relief valve undertaken following any turbocharger malfunction. activates to relieve excess system pressure. Retractable Landing Gear Controls and Position Indicators Landing gear position is controlled by a switch on the The primary benefits of being able to retract the landing gear flightdeck panel. In most airplanes, the gear switch is shaped are increased climb performance and higher cruise airspeeds like a wheel in order to facilitate positive identification and due to the resulting decrease in drag. Retractable landing gear to differentiate it from other flightdeck controls. systems may be operated either hydraulically or electrically or may employ a combination of the two systems. Warning Landing gear position indicators vary with different make and indicators are provided in the flightdeck to show the pilot model airplanes. However, the most common types of landing when the wheels are down and locked and when they are up gear position indicators utilize a group of lights. One type and locked or if they are in intermediate positions. Systems consists of a group of three green lights, which illuminate when for emergency operation are also provided. The complexity the landing gear is down and locked. [Figure 11-10] Another of the retractable landing gear system requires that specific type consists of one green light to indicate when the landing operating procedures be adhered to and that certain operating gear is down and an amber light to indicate when the gear is limitations not be exceeded. up. [Figure 11-11] Still other systems incorporate a red or amber light to indicate when the gear is in transit or unsafe for Landing Gear Systems landing. [Figure 11-12] The lights are usually of the “press to An electrical landing gear retraction system utilizes an test” type, and the bulbs are interchangeable. [Figure 11-10] electrically-driven motor for gear operation. The system is basically an electrically-driven jack for raising and lowering Other types of landing gear position indicators consist of the gear. When a switch in the flightdeck is moved to the UP tab-type indicators with markings “UP” to indicate the gear position, the electric motor operates. Through a system of is up and locked, a display of red and white diagonal stripes shafts, gears, adapters, an actuator screw, and a torque tube, to show when the gear is unlocked, or a silhouette of each a force is transmitted to the drag strut linkages. Thus, the gear gear to indicate when it locks in the DOWN position. retracts and locks. Struts are also activated that open and close the gear doors. If the switch is moved to the DOWN position, Landing Gear Safety Devices the motor reverses and the gear moves down and locks. Once Most airplanes with a retractable landing gear have a gear activated, the gear motor continues to operate until an up or warning horn that sounds when the airplane is configured down limit switch on the motor’s gearbox is tripped. for landing and the landing gear is not down and locked. Normally, the horn is linked to the throttle or flap position A hydraulic landing gear retraction system utilizes pressurized and/or the airspeed indicator so that when the airplane is hydraulic fluid to actuate linkages to raise and lower the gear. below a certain airspeed, configuration, or power setting with When a switch in the flightdeck is moved to the UP position, the gear retracted, the warning horn sounds. hydraulic fluid is directed into the gear up line. The fluid flows through sequenced valves and down locks to the gear actuating cylinders. A similar process occurs during gear 11-11

Landing gear indicator (top) illuminated (red) this way, if the landing gear switch in the flightdeck is placed in the RETRACT position when weight is on the gear, the NOSE Landing gear indicator gear remains extended, and the warning horn may sound as GEAR (bottom) illuminated an alert to the unsafe condition. Once the weight is off the GNOEASRE (green)—related gear gear, however, such as on takeoff, the safety switch releases GLEEAFTR RGIEGAHRT down and locked and the gear retracts. LEFT RIGHT GEAR GEAR Many airplanes are equipped with additional safety devices to prevent collapse of the gear when the airplane is on the UP ground. These devices are called ground locks. One common type is a pin installed in aligned holes drilled in two or more L units of the landing gear support structure. Another type is a spring-loaded clip designed to fit around and hold two or A more units of the support structure together. All types of ground locks usually have red streamers permanently attached N to them to readily indicate whether or not they are installed. D Emergency Gear Extension Systems The emergency extension system lowers the landing gear if the I main power system fails. Some airplanes have an emergency release handle in the flightdeck, which is connected through N OFF LANDING GEAR a mechanical linkage to the gear up locks. When the handle G LIMIT (IAS) is operated, it releases the up locks and allows the gear to free fall or extend under their own weight. [Figure 11-13] G OPERATING E EXTEND 270—.8M On other airplanes, release of the up lock is accomplished A using compressed gas, which is directed to up lock release R RETRACT 235K cylinders. In some airplanes, design configurations make EXTENDED 320—.82K emergency extension of the landing gear by gravity and air DN loads alone impossible or impractical. In these airplanes, FLAPS LIMIT (IAS) provisions are included for forceful gear extension in an Override Landing gear lever emergency. Some installations are designed so that either trigger hydraulic fluid or compressed gas provides the necessary Landing gear limit pressure, while others use a manual system, such as a LANDING GEAR speed placard hand crank for emergency gear extension. [Figure 11-14] LIMIT (IAS) Hydraulic pressure for emergency operation of the landing gear may be provided by an auxiliary hand pump, an OPERATING accumulator, or an electrically-powered hydraulic pump EXTEND 270 .8M depending on the design of the airplane. RETRACR 235K EXTENDED 320 .82K FLAPS LIMIT (IAS) Figure 11-10. Typical landing gear switch with three light indicator. Accidental retraction of a landing gear may be prevented Operational Procedures by such devices as mechanical down locks, safety switches, Preflight and ground locks. Mechanical down locks are built-in Because of their complexity, retractable landing gear components of a gear retraction system and are operated demands a close inspection prior to every flight. The automatically by the gear retraction system. To prevent inspection should begin inside the flightdeck. First, make accidental operation of the down locks and inadvertent certain that the landing gear selector switch is in the GEAR landing gear retraction while the airplane is on the ground, DOWN position. Then, turn on the battery master switch and electrically-operated safety switches are installed. ensure that the landing gear position indicators show that the gear is DOWN and locked. A landing gear safety switch, sometimes referred to as a squat switch, is usually mounted in a bracket on one the main gear External inspection of the landing gear consists of checking shock struts. [Figure 11-12] When the strut is compressed individual system components. [Figure 11-14] The landing by the weight of the airplane, the switch opens the electrical gear, wheel well, and adjacent areas should be clean and free circuit to the motor or mechanism that powers retraction. In 11-12

GEAR GEAR UP UP GEAR DOWN TAXI LANDING GEAR 60 TAXI LANDING DOWN 5 88 5 8 8 5 15 60 5 15 Figure 11-11. Landing gear handles and single and multiple light indictor. of mud and debris. Dirty switches and valves may cause false lines for signs of chafing and leakage at attach points. Warning safe light indications or interrupt the extension cycle before system micro switches (squat switches) are checked for the landing gear is completely down and locked. The wheel cleanliness and security of attachment. Actuating cylinders, wells should be clear of any obstructions, as foreign objects sprockets, universal joints, drive gears, linkages, and any may damage the gear or interfere with its operation. Bent other accessible components are checked for condition and gear doors may be an indication of possible problems with obvious defects. The airplane structure to which the landing normal gear operation. gear is attached is checked for distortion, cracks, and general condition. All bolts and rivets should be intact and secure. Ensure shock struts are properly inflated and that the pistons are clean. Check main gear and nose gear up lock and down Takeoff and Climb lock mechanisms for general condition. Power sources and Normally, the landing gear is retracted after lift-off when retracting mechanisms are checked for general condition, the airplane has reached an altitude where, in the event of an obvious defects, and security of attachment. Check hydraulic engine failure or other emergency requiring an aborted takeoff, Lock release solenoid Lock-pin SaSfaefteytyswsiwtcithch B28aVtteDrCy Safety switch Landing gear selector valve Figure 11-12. Landing gear safety switch. 11-13

Compressed Gas Hand Pump Hand Crank Figure 11-13. Typical emergency gear extension systems. Figure 11-14. Retractable landing gear inspection checkpoints. 11-14

the airplane could no longer be landed on the runway. This They are published in the AFM/POH for the particular procedure, however, may not apply to all situations. Preplan airplane and are usually listed on placards in the flightdeck. landing gear retraction taking into account the following: [Figure 11-15] The maximum landing extended speed (VLE) is the maximum speed at which the airplane can be flown • Length of the runway with the landing gear extended. The maximum landing gear operating speed (VLO) is the maximum speed at which the • Climb gradient landing gear may be operated through its cycle. • Obstacle clearance requirements The landing gear is extended by placing the gear selector switch in the GEAR DOWN position. As the landing gear • The characteristics of the terrain beyond the departure extends, the airspeed decreases and the pitch attitude may end of the runway change. During the several seconds it takes for the gear to extend, be attentive to any abnormal sounds or feel. Confirm • The climb characteristics of the particular airplane. that the landing gear has extended and locked by the normal sound and feel of the system operation, as well as by the gear For example, in some situations it may be preferable, in the position indicators in the flightdeck. Unless the landing gear event of an engine failure, to make an off airport forced landing has been previously extended to aid in a descent to traffic with the gear extended in order to take advantage of the energy pattern altitude, the landing gear should be extended by the absorbing qualities of the terrain (see Chapter 19, “Emergency time the airplane reaches a point on the downwind leg that is Procedures”). In which case, a delay in retracting the landing opposite the point of intended landing. Establish a standard gear after takeoff from a short runway may be warranted. In procedure consisting of a specific position on the downwind other situations, obstacles in the climb path may warrant a leg at which to lower the landing gear. Strict adherence to this timely gear retraction after takeoff. Also, in some airplanes the procedure aids in avoiding unintentional gear up landings. initial climb pitch attitude is such that any view of the runway remaining is blocked, making an assessment of the feasibility of touching down on the remaining runway difficult. Avoid premature landing gear retraction and do not retract Operation of an airplane equipped with a retractable landing the landing gear until a positive rate of climb is indicated gear requires the deliberate, careful, and continued use of on the flight instruments. If the airplane has not attained an appropriate checklist. When on the downwind leg, make a positive rate of climb, there is always the chance it may it a habit to complete the before landing checklist for that settle back onto the runway with the gear retracted. This is airplane. This accomplishes two purposes. It ensures that especially so in cases of premature lift-off. Remember that action has been taken to lower the gear and establishes leaning forward to reach the landing gear selector may result awareness so that the gear down indicators can be rechecked in inadvertent forward pressure on the yoke, which causes prior to landing. the airplane to descend. Unless good operating practices dictate otherwise, the landing As the landing gear retracts, airspeed increases and the roll should be completed and the airplane should be clear airplane’s pitch attitude may change. The gear may take of the runway before any levers or switches are operated. several seconds to retract. Gear retraction and locking (and gear extension and locking) is accompanied by sound and feel that are unique to the specific make and model airplane. Become familiar with the sound and feel of normal gear retraction so that any abnormal gear operation can be readily recognized. Abnormal landing gear retraction is most often a clear sign that the gear extension cycle will also be abnormal. Approach and Landing Figure 11-15. Placarded gear speeds in the cockpit. The operating loads placed on the landing gear at higher airspeeds may cause structural damage due to the forces of the airstream. Limiting speeds, therefore, are established for gear operation to protect the gear components from becoming overstressed during flight. These speeds may not be found on the airspeed indicator. 11-15

This technique greatly reduces the chance of inadvertently determine if the bulb(s) in the display is good. Check retracting the landing gear while on the ground. Wait until to see if spare bulbs are available in the airplane spare after rollout and clearing the runway to focus attention on bulb supply as part of the preflight inspection. the after landing checklist. This practice allows for positive identification of the proper controls. • Be familiar with and aware of the sounds and feel of a properly operating landing gear system. When transitioning to retractable gear airplanes, it is Transition Training important to consider some frequent pilot errors. These include pilots that have: Transition to a complex airplane or a high-performance airplane should be accomplished through a structured course • Neglected to extend landing gear of training administered by a competent and qualified flight instructor. The training should be accomplished in accordance • Inadvertently retracted landing gear with a ground and flight training syllabus. [Figure 11-16] • Activated gear but failed to check gear position This sample syllabus for transition training is an example. The arrangement of the subject matter may be changed and the • Misused emergency gear system emphasis shifted to fit the qualifications of the transitioning pilot, the airplane involved, and the circumstances of the • Retracted gear prematurely on takeoff training situation. The goal is to ensure proficiency standards are achieved. These standards are contained in the Practical • Extended gear too late Test Standards (PTS) or Airmen Certification Standard (ACS) as appropriate for the certificate that the transitioning These mistakes are not only committed by pilots who have pilot holds or is working towards. just transitioned to complex aircraft, but also by pilots who have developed a sense of complacency over time. In order The training times indicated in the syllabus are for illustration to minimize the chances of a landing gear-related mishap: purposes. Actual times must be based on the capabilities of the pilot. The time periods may be minimal for pilots with • Use an appropriate checklist. (A condensed checklist higher qualifications or increased for pilots who do not meet mounted in view is a reminder for its use and easy certification requirements or have had little recent flight reference can be especially helpful.) experience. • Be familiar with, and periodically review, the Chapter Summary landing gear emergency extension procedures for the particular airplane. Flying a complex or high-performance airplane requires a pilot to further divide his or her attention during the most • Be familiar with the landing gear warning horn and critical phases of flight: take-off and landing. The knowledge, warning light systems for the particular airplane. judgment, and piloting skills required to fly these airplanes Use the horn system to cross-check the warning light must be developed. It is essential that adequate training is system when an unsafe condition is noted. • Review the procedure for replacing light bulbs in the landing gear warning light displays for the particular airplane, so that you can properly replace a bulb to Ground Instruction Flight Instruction One hour One hour 1. Operations sections of flight manual 1. Flight training maneuvers 2. Line inspection 2. Takeoffs, landings and go-arounds 3. Cockpit familiarization One hour One hour 1. Emergency operations 1. Aircraft loading, limitations and servicing 2. Control by reference to instruments 2. instruments, radio and special equipment 3. Use of radio and autopilot 3. Aircraft systems One hour One hour 1. Short and soft-field takeoffs and landings 1. Performance section of flight manual 2. Maximum performance operations 2. Cruise control 3. Review Figure 11-16. Sample transition training syllabus. 11-16

received to ensure a complete understanding of the systems, their operation (both normal and emergency), and operating limitations. 11-17

11-18

TCharptear12nsition to Multiengine Airplanes Introduction This chapter is devoted to the factors associated with the operation of small multiengine airplanes. For the purpose of this handbook, a “small” multiengine airplane is a reciprocating or turbopropeller-powered airplane with a maximum certificated takeoff weight of 12,500 pounds or less. This discussion assumes a conventional design with two engines—one mounted on each wing. Reciprocating engines are assumed unless otherwise noted. The term “light-twin,” although not formally defined in the regulations, is used herein as a small multiengine airplane with a maximum certificated takeoff weight of 6,000 pounds or less. There are several unique characteristics of multiengine airplanes that make them worthy of a separate class rating. Knowledge of these factors and proficient flight skills are a key to safe flight in these airplanes. This chapter deals extensively with the numerous aspects of one engine inoperative (OEI) flight. However, pilots are strongly cautioned not to place undue emphasis on mastery of OEI flight as the sole key to flying multiengine airplanes safely. The inoperative engine information that follows is extensive only because this chapter emphasizes the differences between flying multiengine airplanes as contrasted to single-engine airplanes. 12-1

The modern, well-equipped multiengine airplane can be Above the single-engine absolute ceiling, VYSE yields remarkably capable under many circumstances. But, as the minimum rate of sink. with single-engine airplanes, it must be flown prudently by a current and competent pilot to achieve the highest possible • VSSE—safe, intentional OEI speed—originally known level of safety. as safe single-engine speed, now formally defined in Title 14 of the Code of Federal Regulations (14 CFR) This chapter contains information and guidance on the part 23, Airworthiness Standards, and required to be performance of certain maneuvers and procedures in small established and published in the AFM/POH. It is the multiengine airplanes for the purposes of flight training minimum speed to intentionally render the critical and pilot certification testing. The airplane manufacturer engine inoperative. is the final authority on the operation of a particular make and model airplane. Flight instructors and students should • VREF—reference landing speed—an airspeed used use the Federal Aviation Administration’s Approved Flight for final approach, which adjust the normal approach Manual (AFM) and/or the Pilot’s Operating Handbook (POH) speed for winds and gusty conditions. VREF is 1.3 times but realize that the airplane manufacturer’s guidance and the stall speed in the landing configuration. procedures take precedence. • VMC—minimum control speed with the critical engine General inoperative—marked with a red radial line on most airspeed indicators. The minimum speed at which The basic difference between operating a multiengine directional control can be maintained under a very airplane and a single-engine airplane is the potential problem specific set of circumstances outlined in 14 CFR part involving an engine failure. The penalties for loss of an engine 23, Airworthiness Standards. Under the small airplane are twofold: performance and control. The most obvious certification regulations currently in effect, the flight problem is the loss of 50 percent of power, which reduces test pilot must be able to (1) stop the turn that results climb performance 80 to 90 percent, sometimes even more. when the critical engine is suddenly made inoperative The other is the control problem caused by the remaining within 20° of the original heading, using maximum thrust, which is now asymmetrical. Attention to both these rudder deflection and a maximum of 5° bank, and factors is crucial to safe OEI flight. The performance and (2) thereafter, maintain straight flight with not more systems redundancy of a multiengine airplane is a safety than a 5° bank. There is no requirement in this advantage only to a trained and proficient pilot. determination that the airplane be capable of climbing at this airspeed. VMC only addresses directional Terms and Definitions control. Further discussion of VMC as determined during airplane certification and demonstrated in pilot Pilots of single-engine airplanes are already familiar with many training follows in minimum control airspeed (VMC) performance “V” speeds and their definitions. Twin-engine demonstration. [Figure 12-1] airplanes have several additional V-speeds unique to OEI operation. These speeds are differentiated by the notation “SE” Unless otherwise noted, when V-speeds are given in the for single engine. A review of some key V-speeds and several AFM/POH, they apply to sea level, standard day conditions new V-speeds unique to twin-engine airplanes are listed below. at maximum takeoff weight. Performance speeds vary with aircraft weight, configuration, and atmospheric conditions. • VR—rotation speed—speed at which back pressure is The speeds may be stated in statute miles per hour (mph) applied to rotate the airplane to a takeoff attitude. or knots (kt), and they may be given as calibrated airspeeds (CAS) or indicated airspeeds (IAS). As a general rule, the • VLOF—lift-off speed—speed at which the airplane leaves newer AFM/POHs show V-speeds in knots indicated airspeed the surface. (NOTE: Some manufacturers reference (KIAS). Some V-speeds are also stated in knots calibrated takeoff performance data to VR, others to VLOF.) airspeed (KCAS) to meet certain regulatory requirements. Whenever available, pilots should operate the airplane from • VX—best angle of climb speed—speed at which the published indicated airspeeds. airplane gains the greatest altitude for a given distance of forward travel. With regard to climb performance, the multiengine airplane, particularly in the takeoff or landing configuration, may be • VXSE—best angle-of-climb speed with OEI. considered to be a single-engine airplane with its powerplant divided into two units. There is nothing in 14 CFR part 23 • VY—best rate of climb speed—speed at which the that requires a multiengine airplane to maintain altitude while airplane gains the most altitude for a given unit of time. in the takeoff or landing configuration with OEI. In fact, • VYSE—best rate of climb speed with OEI. Marked with a blue radial line on most airspeed indicators. 12-2

IAS There is a dramatic performance loss associated with the loss of an engine, particularly just after takeoff. Any airplane’s 260 40 climb performance is a function of thrust horsepower, which AIRSPEED is in excess of that required for level flight. In a hypothetical 200 250 KNOTS twin with each engine producing 200 thrust horsepower, 60 assume that the total level flight thrust horsepower required is 175. In this situation, the airplane would ordinarily have 180 200 80 a reserve of 225 thrust horsepower available for climb. Loss of one engine would leave only 25 (200 minus 175) thrust 160 TAS 100 horsepower available for climb, a drastic reduction. Sea level 140 120 rate of climb performance losses of at least 80 to 90 percent, 160 even under ideal circumstances, are typical for multiengine 140 airplanes in OEI flight. Figure 12-1. Airspeed indicator markings for a multiengine Operation of Systems airplane. This section deals with systems that are generally found on many twins are not required to do this in any configuration, multiengine airplanes. Multiengine airplanes share many even at sea level. features with complex single-engine airplanes. There are certain systems and features covered that are generally unique to airplanes with two or more engines. The current 14 CFR part 23 single-engine climb performance Propellers requirements for reciprocating engine-powered multiengine The propellers of the multiengine airplane may outwardly airplanes are as follows. appear to be identical in operation to the constant-speed propellers of many single-engine airplanes, but this is not the • More than 6,000 pounds maximum weight and/or case. The propellers of multiengine airplanes are featherable, VSO more than 61 knots: the single-engine rate of to minimize drag in the event of an engine failure. Depending climb in feet per minute (fpm) at 5,000 feet mean upon single-engine performance, this feature often permits sea level (MSL) must be equal to at least .027 VSO 2. continued flight to a suitable airport following an engine For airplanes type certificated February 4, 1991, or failure. To feather a propeller is to stop engine rotation with thereafter, the climb requirement is expressed in terms the propeller blades streamlined with the airplane’s relative of a climb gradient, 1.5 percent. The climb gradient wind, thus to minimize drag. [Figure 12-2] is not a direct equivalent of the .027 VSO 2 formula. Do not confuse the date of type certification with the Feathering is necessary because of the change in parasite airplane’s model year. The type certification basis of drag with propeller blade angle. [Figure 12-3] When the many multiengine airplanes dates back to the Civil propeller blade angle is in the feathered position, the change Aviation Regulations (CAR) 3. in parasite drag is at a minimum and, in the case of a typical multiengine airplane, the added parasite drag from a single • 6,000 pounds or less maximum weight and VSO feathered propeller is a relatively small contribution to the 61 knots or less: the single-engine rate of climb at airplane total drag. 5,000 feet MSL must simply be determined. The rate of climb could be a negative number. There is no At the smaller blade angles near the flat pitch position, the requirement for a single-engine positive rate of climb drag added by the propeller is very large. At these small blade at 5,000 feet or any other altitude. For light-twins angles, the propeller windmilling at high rates per minute type certificated February 4, 1991, or thereafter, the (rpm) can create such a tremendous amount of drag that the single-engine climb gradient (positive or negative) is airplane may be uncontrollable. The propeller windmilling simply determined. at high speed in the low range of blade angles can produce an increase in parasite drag, which may be as great as the Rate of climb is the altitude gain per unit of time, while climb parasite drag of the basic airplane. gradient is the actual measure of altitude gained per 100 feet of horizontal travel, expressed as a percentage. An altitude gain of 1.5 feet per 100 feet of travel (or 15 feet per 1,000, or 150 feet per 10,000) is a climb gradient of 1.5 percent. 12-3

Change in Equivalent Parasite Drag Windmilling propeller Stationary propeller Feathered position Flat blade position 0 15 30 45 60 90 Propeller Blade Angle Figure 12-3. Propeller drag contribution. the counterweights, is generally slightly greater than the aerodynamic forces. Oil pressure from the propeller governor is used to counteract the counterweights and drives the blade angles to low pitch, high rpm. A reduction in oil pressure causes the rpm to be reduced from the influence of the counterweights. [Figure 12-4] Low Pitch High Pitch Full Feathered 90° To feather the propeller, the propeller control is brought fully aft. All oil pressure is dumped from the governor, and the Figure 12-2. Feathered propeller. counterweights drive the propeller blades towards feather. As centrifugal force acting on the counterweights decays from As a review, the constant-speed propellers on almost all decreasing rpm, additional forces are needed to completely single-engine airplanes are of the non-feathering, oil- feather the blades. This additional force comes from either pressure-to-increase-pitch design. In this design, increased a spring or high-pressure air stored in the propeller dome, oil pressure from the propeller governor drives the blade which forces the blades into the feathered position. The entire angle towards high pitch, low rpm. process may take up to 10 seconds. In contrast, the constant-speed propellers installed on most Feathering a propeller only alters blade angle and stops multiengine airplanes are full feathering, counterweighted, engine rotation. To completely secure the engine, the pilot oil-pressure-to-decrease-pitch designs. In this design, must still turn off the fuel (mixture, electric boost pump, increased oil pressure from the propeller governor drives and fuel selector), ignition, alternator/generator, and close the blade angle towards low pitch, high rpm—away from the cowl flaps. If the airplane is pressurized, there may also the feather blade angle. In effect, the only thing that keeps be an air bleed to close for the failed engine. Some airplanes these propellers from feathering is a constant supply of high- are equipped with firewall shutoff valves that secure several pressure engine oil. This is a necessity to enable propeller of these systems with a single switch. feathering in the event of a loss of oil pressure or a propeller governor failure. Completely securing a failed engine may not be necessary or even desirable depending upon the failure mode, altitude, The aerodynamic forces alone acting upon a windmilling and time available. The position of the fuel controls, ignition, propeller tend to drive the blades to low pitch, high rpm. and alternator/generator switches of the failed engine has no Counterweights attached to the shank of each blade tend effect on aircraft performance. There is always the distinct to drive the blades to high pitch, low rpm. Inertia, or possibility of manipulating the incorrect switch under apparent force (called centrifugal force) acting through conditions of haste or pressure. To unfeather a propeller, the engine must be rotated so that oil pressure can be generated to move the propeller blades 12-4

1 Counterweight action 6 62 4 Hydraulic force 3 Aerodynamic force 5 Nitrogen pressure or spring force, and counterweight action 1 High-pressure oil enters the cylinder through the center of 4 The forks push the pitch-change pin of each blade toward the propeller shaft and piston rod. The propeller control the front of the hub causing the blades to twist toward the regulates the flow of high-pressure oil from a governor. low-pitch position. 2 A hydraulic piston in the hub of the propeller is connected 5 A nitrogen pressure charge or mechanical spring in the to each blade by a piston rod. This rod is attached to forks front of the hub opposes the oil pressure and causes the that slide over the pitch-change pin mounted in the root of propeller to move toward high-pitch. each blade. 6 Counterweights also cause the blades to move toward the 3 The oil pressure moves the piston toward the front of the high-pitch and feather positions. The counterweights cylinder, moving the piston rod and forks forward. counteract the aerodynamic twisting force that tries to move the blades toward a low-pitch angle. Figure 12-4. Pitch change forces. from the feathered position. The ignition is turned on prior to pin senses a lack of centrifugal force from propeller rotation engine rotation with the throttle at low idle and the mixture and falls into place, preventing the blades from feathering. rich. With the propeller control in a high rpm position, the Therefore, if a propeller is to be feathered, it must be done starter is engaged. The engine begins to windmill, start, before engine rpm decays below approximately 800. On one and run as oil pressure moves the blades out of feather. As popular model of turboprop engine, the propeller blades do, the engine starts, the propeller rpm should be immediately in fact, feather with each shutdown. This propeller is not reduced until the engine has had several minutes to warm up; equipped with such centrifugally-operated pins due to a the pilot should monitor cylinder head and oil temperatures. unique engine design. In any event, the AFM/POH procedures should be followed An unfeathering accumulator is a device that permits starting for the exact unfeathering procedure. Both feathering and a feathered engine in flight without the use of the electric starting a feathered reciprocating engine on the ground are starter. An accumulator is any device that stores a reserve strongly discouraged by manufacturers due to the excessive of high pressure. On multiengine airplanes, the unfeathering stress and vibrations generated. accumulator stores a small reserve of engine oil under pressure from compressed air or nitrogen. To start a feathered As just described, a loss of oil pressure from the propeller engine in flight, the pilot moves the propeller control out of governor allows the counterweights, spring, and/or dome the feather position to release the accumulator pressure. The charge to drive the blades to feather. Logically then, the oil flows under pressure to the propeller hub and drives the propeller blades should feather every time an engine is shut blades toward the high rpm, low pitch position, whereupon down as oil pressure falls to zero. Yet, this does not occur. the propeller usually begins to windmill. (On some airplanes, Preventing this is a small pin in the pitch changing mechanism an assist from the electric starter may be necessary to initiate of the propeller hub that does not allow the propeller blades rotation and completely unfeather the propeller.) If fuel and to feather once rpm drops below approximately 800. The ignition are present, the engine starts and runs. For airplanes 12-5

used in training, this saves much electric starter and battery POH describes crossfeed limitations and procedures that vary wear. High oil pressure from the propeller governor recharges significantly among multiengine airplanes. the accumulator just moments after engine rotation begins. Checking crossfeed operation on the ground with a quick Propeller Synchronization repositioning of the fuel selectors does nothing more than Many multiengine airplanes have a propeller synchronizer ensure freedom of motion of the handle. To actually check (prop sync) installed to eliminate the annoying “drumming” crossfeed operation, a complete, functional crossfeed system or “beat” of propellers whose rpm are close, but not precisely check should be accomplished. To do this, each engine should the same. To use prop sync, the propeller rpm is coarsely be operated from its crossfeed position during the run-up. The matched by the pilot and the system is engaged. The prop engines should be checked individually and allowed to run at sync adjusts the rpm of the “slave” engine to precisely moderate power (1,500 rpm minimum) for at least 1 minute match the rpm of the “master” engine and then maintains to ensure that fuel flow can be established from the crossfeed that relationship. source. Upon completion of the check, each engine should be operated for at least 1 minute at moderate power from the main The prop sync should be disengaged when the pilot selects a (takeoff) fuel tanks to reconfirm fuel flow prior to takeoff. new propeller rpm and then re-engaged after the new rpm is set. The prop sync should always be off for takeoff, landing, This suggested check is not required prior to every flight. and single-engine operation. The AFM/POH should be Crossfeed lines are ideal places for water and debris to consulted for system description and limitations. accumulate unless they are used from time to time and drained using their external drains during preflight. Crossfeed A variation on the propeller synchronizer is the propeller is ordinarily not used for completing single-engine flights synchrophaser. Prop synchrophase acts much like a when an alternate airport is readily at hand, and it is never synchronizer to precisely match rpm, but the synchrophaser used during takeoff or landings. goes one step further. It not only matches rpm but actually compares and adjusts the positions of the individual blades Combustion Heater of the propellers in their arcs. There can be significant Combustion heaters are common on multiengine airplanes. propeller noise and vibration reductions with a propeller A combustion heater is best described as a small furnace that synchrophaser. From the pilot’s perspective, operation of burns gasoline to produce heated air for occupant comfort a propeller synchronizer and a propeller synchrophaser are and windshield defogging. Most are thermostatically operated very similar. A synchrophaser is also commonly referred to as and have a separate hour meter to record time in service prop sync, although that is not entirely correct nomenclature for maintenance purposes. Automatic over temperature from a technical standpoint. protection is provided by a thermal switch mounted on the unit that cannot be accessed in flight. This requires the pilot As a pilot aid to manually synchronizing the propellers, some or mechanic to actually visually inspect the unit for possible twins have a small gauge mounted in or by the tachometer(s) heat damage in order to reset the switch. with a propeller symbol on a disk that spins. The pilot manually fine tunes the engine rpm so as to stop disk rotation, When finished with the combustion heater, a cool-down thereby synchronizing the propellers. This is a useful backup period is required. Most heaters require that outside air be to synchronizing engine rpm using the audible propeller permitted to circulate through the unit for at least 15 seconds beat. This gauge is also found installed with most propeller in flight or that the ventilation fan can be operated for at least synchronizer and synchrophase systems. Some synchrophase 2 minutes on the ground. Failure to provide an adequate cool systems use a knob for the pilot to control the phase angle. down usually trips the thermal switch and renders the heater inoperative until the switch is reset. Fuel Crossfeed Fuel crossfeed systems are also unique to multiengine Flight Director/Autopilot airplanes. Using crossfeed, an engine can draw fuel from a Flight director/autopilot (FD/AP) systems are common on the fuel tank located in the opposite wing. better-equipped multiengine airplanes. The system integrates pitch, roll, heading, altitude, and radio navigation signals in On most multiengine airplanes, operation in the crossfeed a computer. The outputs, called computed commands, are mode is an emergency procedure used to extend airplane displayed on a flight command indicator (FCI). The FCI range and endurance in OEI flight. There are a few models replaces the conventional attitude indicator on the instrument that permit crossfeed as a normal, fuel balancing technique panel. The FCI is occasionally referred to as a flight director in normal operation, but these are not common. The AFM/ indicator (FDI) or as an attitude director indicator (ADI). 12-6

The entire flight director/autopilot system is sometimes Yaw Damper called an integrated flight control system (IFCS) by some The yaw damper is a servo that moves the rudder in response manufacturers. Others may use the term automatic flight to inputs from a gyroscope or accelerometer that detects yaw control system (AFCS). rate. The yaw damper minimizes motion about the vertical axis caused by turbulence. (Yaw dampers on swept wing The FD/AP system may be employed at the following airplanes provide another, more vital function of damping different levels: dutch roll characteristics.) Occupants feel a smoother ride, particularly if seated in the rear of the airplane, when the yaw • Off (raw data) damper is engaged. The yaw damper should be off for takeoff and landing. There may be additional restrictions against its • Flight director (computed commands) use during single-engine operation. Most yaw dampers can be engaged independently of the autopilot. • Autopilot Alternator/Generator With the system off, the FCI operates as an ordinary attitude Alternator or generator paralleling circuitry matches the indicator. On most FCIs, the command bars are biased out of output of each engine’s alternator/generator so that the view when the FD is off. The pilot maneuvers the airplane electrical system load is shared equally between them. In the as though the system were not installed. event of an alternator/generator failure, the inoperative unit can be isolated and the entire electrical system powered from To maneuver the airplane using the FD, the pilot enters the the remaining one. Depending upon the electrical capacity desired modes of operation (heading, altitude, navigation of the alternator/generator, the pilot may need to reduce the (NAV) intercept, and tracking) on the FD/AP mode electrical load (referred to as load shedding) when operating controller. The computed flight commands are then displayed on a single unit. The AFM/POH contains system description to the pilot through either a single-cue or dual-cue system and limitations. in the FCI. On a single-cue system, the commands are indicated by “V” bars. On a dual-cue system, the commands Nose Baggage Compartment are displayed on two separate command bars, one for pitch Nose baggage compartments are common on multiengine and one for roll. To maneuver the airplane using computed airplanes (and are even found on a few single-engine commands, the pilot “flies” the symbolic airplane of the FCI airplanes). There is nothing strange or exotic about a nose to match the steering cues presented. baggage compartment, and the usual guidance concerning observation of load limits applies. Pilots occasionally neglect On most systems, to engage the autopilot the FD must first to secure the latches properly. When improperly secured, the be operating. At any time thereafter, the pilot may engage door opens and the contents may be drawn out, usually into the autopilot through the mode controller. The autopilot then the propeller arc and just after takeoff. Even when the nose maneuvers the airplane to satisfy the computed commands baggage compartment is empty, airplanes have been lost of the FD. when the pilot became distracted by the open door. Security of the nose baggage compartment latches and locks is a vital Like any computer, the FD/AP system only does what it preflight item. is told. The pilot must ensure that it has been programmed properly for the particular phase of flight desired. The Most airplanes continue to fly with a nose baggage door open. armed and/or engaged modes are usually displayed on the There may be some buffeting from the disturbed airflow, and mode controller or separate annunciator lights. When the there is an increase in noise. Pilots should never become so airplane is being hand-flown, if the FD is not being used at preoccupied with an open door (of any kind) that they fail any particular moment, it should be off so that the command to fly the airplane. bars are pulled from view. Inspection of the compartment interior is also an important Prior to system engagement, all FD/AP computer and trim preflight item. More than one pilot has been surprised to find a checks should be accomplished. Many newer systems supposedly empty compartment packed to capacity or loaded cannot be engaged without the completion of a self-test. with ballast. The tow bars, engine inlet covers, windshield sun The pilot must also be very familiar with various methods screens, oil containers, spare chocks, and miscellaneous small of disengagement, both normal and emergency. System hand tools that find their way into baggage compartments details, including approvals and limitations, can be found should be secured to prevent damage from shifting in flight. in the supplements section of the AFM/POH. Additionally, many avionics manufacturers can provide informative pilot operating guides upon request. 12-7

Anti-Icing/Deicing usually plumbed to a non-pressurized baggage compartment. Anti-icing/deicing equipment is frequently installed on The pilot must activate the alternate static source by opening multiengine airplanes and consists of a combination of a valve or a fitting in the flightdeck. Upon activation, the different systems. These may be classified as either anti- airspeed indicator, altimeter, and the vertical speed indicator icing or deicing, depending upon function. The presence (VSI) is affected and reads somewhat in error. A correction of anti-icing and deicing equipment, even though it may table is frequently provided in the AFM/POH. appear elaborate and complete, does not necessarily mean that the airplane is approved for flight in icing conditions. Anti-icing/deicing equipment only eliminates ice from the The AFM/POH, placards, and even the manufacturer should protected surfaces. Significant ice accumulations may form be consulted for specific determination of approvals and on unprotected areas, even with proper use of anti-ice and limitations. Anti-icing equipment is provided to prevent deice systems. Flight at high angles of attack (AOA) or even ice from forming on certain protected surfaces. Anti-icing normal climb speeds permit significant ice accumulations on equipment includes heated pitot tubes, heated or non- lower wing surfaces, which are unprotected. Many AFM/ icing static ports and fuel vents, propeller blades with POHs mandate minimum speeds to be maintained in icing electrothermal boots or alcohol slingers, windshields with conditions. Degradation of all flight characteristics and large alcohol spray or electrical resistance heating, windshield performance losses can be expected with ice accumulations. defoggers, and heated stall warning lift detectors. On many Pilots should not rely upon the stall warning devices for turboprop engines, the “lip” surrounding the air intake is adequate stall warning with ice accumulations. heated either electrically or with bleed air. In the absence of AFM/POH guidance to the contrary, anti-icing equipment Ice accumulates unevenly on the airplane. It adds weight should be actuated prior to flight into known or suspected and drag (primarily drag) and decreases thrust and lift. Even icing conditions. wing shape affects ice accumulation; thin airfoil sections are more prone to ice accumulation than thick, highly- Deicing equipment is generally limited to pneumatic boots on cambered sections. For this reason, certain surfaces, such wing and tail leading edges. Deicing equipment is installed as the horizontal stabilizer, are more prone to icing than the to remove ice that has already formed on protected surfaces. wing. With ice accumulations, landing approaches should Upon pilot actuation, the boots inflate with air from the be made with a minimum wing flap setting (flap extension pneumatic pumps to break off accumulated ice. After a few increases the AOA of the horizontal stabilizer) and with an seconds of inflation, they are deflated back to their normal added margin of airspeed. Sudden and large configuration position with the assistance of a vacuum. The pilot monitors and airspeed changes should be avoided. the buildup of ice and cycles the boots as directed in the AFM/ POH. An ice light on the left engine nacelle allows the pilot Unless otherwise recommended in the AFM/POH, the to monitor wing ice accumulation at night. autopilot should not be used in icing conditions. Continuous use of the autopilot masks trim and handling changes that Other airframe equipment necessary for flight in icing occur with ice accumulation. Without this control feedback, conditions includes an alternate induction air source and an the pilot may not be aware of ice accumulation building to alternate static system source. Ice tolerant antennas are also hazardous levels. The autopilot suddenly disconnects when installed. it reaches design limits, and the pilot may find the airplane has assumed unsatisfactory handling characteristics. In the event of impact ice accumulating over normal engine air induction sources, carburetor heat (carbureted engines) The installation of anti-ice/deice equipment on airplanes or alternate air (fuel injected engines) should be selected. Ice without AFM/POH approval for flight into icing conditions buildup on normal induction sources can be detected by a is to facilitate escape when such conditions are inadvertently loss of engine rpm with fixed-pitch propellers and a loss of encountered. Even with AFM/POH approval, the prudent manifold pressure with constant-speed propellers. On some pilot avoids icing conditions to the maximum extent fuel injected engines, an alternate air source is automatically practicable and avoids extended flight in any icing conditions. activated with blockage of the normal air source. No multiengine airplane is approved for flight into severe icing conditions and none are intended for indefinite flight An alternate static system provides an alternate source of in continuous icing conditions. static air for the pitot-static system in the unlikely event that the primary static source becomes blocked. In non- pressurized airplanes, most alternate static sources are plumbed to the cabin. On pressurized airplanes, they are 12-8

Performance and Limitations both engines operating. The airplane has reached its absolute ceiling when climb is no longer possible. Discussion of performance and limitations requires the definition of the following terms. • The single-engine service ceiling is reached when the multiengine airplane can no longer maintain a 50 fpm • Accelerate-stop distance is the runway length required rate of climb with OEI, and its single-engine absolute to accelerate to a specified speed (either VR or VLOF, as ceiling when climb is no longer possible. specified by the manufacturer), experience an engine failure, and bring the airplane to a complete stop. The takeoff in a multiengine airplane should be planned in sufficient detail so that the appropriate action is taken in the • Accelerate-go distance is the horizontal distance event of an engine failure. The pilot should be thoroughly required to continue the takeoff and climb to 50 feet, familiar with the airplane’s performance capabilities and assuming an engine failure at VR or VLOF, as specified limitations in order to make an informed takeoff decision by the manufacturer. as part of the preflight planning. That decision should be reviewed as the last item of the “before takeoff” checklist. • Climb gradient is a slope most frequently expressed in terms of altitude gain per 100 feet of horizontal In the event of an engine failure shortly after takeoff, the distance, whereupon it is stated as a percentage. A decision is basically one of continuing flight or landing, 1.5 percent climb gradient is an altitude gain of one even off-airport. If single-engine climb performance is and one-half feet per 100 feet of horizontal travel. adequate for continued flight, and the airplane has been Climb gradient may also be expressed as a function promptly and correctly configured, the climb after takeoff of altitude gain per nautical mile(NM), or as a ratio of may be continued. If single-engine climb performance is the horizontal distance to the vertical distance (50:1, such that climb is unlikely or impossible, a landing has to for example). Unlike rate of climb, climb gradient is be made in the most suitable area. To be avoided above all affected by wind. Climb gradient is improved with is attempting to continue flight when it is not within the a headwind component and reduced with a tailwind airplane’s performance capability to do so. [Figure 12-6] component. [Figure 12-5] • The all-engine service ceiling of multiengine airplanes is the highest altitude at which the airplane can maintain a steady rate of climb of 100 fpm with Accelerate-go distance 50 feet VR / VLOF Brake release Accelerate-stop distance VLOF 500 feet Brake release 12-9 5,000 feet 10:1 or 10 percent climb gradient Figure 12-5. Accelerate-stop distance, accelerate-go distance, and climb gradient.

Takeoff planning factors include weight and balance, airplane the original accelerate-go distance, with a climb gradient of performance (both single and multiengine), runway length, about 1.6 percent. Any turn, such as to return to the airport, slope and contamination, terrain and obstacles in the area, seriously degrades the already marginal climb performance weather conditions, and pilot proficiency. Most multiengine of the airplane. airplanes have AFM/POH performance charts and the pilot should be highly proficient in their use. Prior to takeoff, Not all multiengine airplanes have published accelerate- the multiengine pilot should ensure that the weight and go distances in their AFM/POH and fewer still publish balance limitations have been observed, the runway length climb gradients. When such information is published, the is adequate, and the normal flightpath clears obstacles and figures have been determined under ideal flight testing terrain. A clear and definite course of action to follow in the conditions. It is unlikely that this performance is duplicated in event of engine failure is essential. service conditions. The regulations do not specifically require that the runway The point of the previous discussion is to illustrate the length be equal to or greater than the accelerate-stop distance. marginal climb performance of a multiengine airplane that Most AFM/POHs publish accelerate-stop distances only as suffers an engine failure shortly after takeoff, even under an advisory. It becomes a limitation only when published ideal conditions. The prudent multiengine pilot should pick a in the limitations section of the AFM/POH. Experienced decision point in the takeoff and climb sequence in advance. multiengine pilots, however, recognize the safety margin If an engine fails before this point the takeoff should be of runway lengths in excess of the bare minimum required rejected, even if airborne, for a landing on whatever runway for normal takeoff. They insist on runway lengths of at or surface lies essentially ahead. If an engine fails after this least accelerate-stop distance as a matter of safety and good point, the pilot should promptly execute the appropriate operating practice. engine failure procedure and continue the climb, assuming the performance capability exists. As a general recommendation, The multiengine pilot must keep in mind that the accelerate-go if the landing gear has not been selected up, the takeoff should distance, as long as it is, has only brought the airplane, under be rejected, even if airborne. ideal circumstances, to a point a mere 50 feet above the takeoff elevation. To achieve even this meager climb, the pilot had to As a practical matter for planning purposes, the option of instantaneously recognize and react to an unanticipated engine continuing the takeoff probably does not exist unless the failure, retract the landing gear, identify and feather the correct published single-engine rate-of-climb performance is at least engine, all the while maintaining precise airspeed control 100 to 200 fpm. Thermal turbulence, wind gusts, engine and and bank angle as the airspeed is nursed to VYSE. Assuming propeller wear, or poor technique in airspeed, bank angle, and flawless airmanship thus far, the airplane has now arrived rudder control can easily negate even a 200 fpm rate of climb. at a point little more than one wingspan above the terrain, assuming it was absolutely level and without obstructions. A pre-takeoff safety brief clearly defines all pre planned emergency actions to all crewmembers. Even if operating For the purpose of illustration, with a near 150 fpm rate of the aircraft alone, the pilot should review and be familiar with climb at a 90-knot VYSE, it takes approximately 3 minutes takeoff emergency considerations. Indecision at the moment to climb an additional 450 feet to reach 500 feet AGL. In an emergency occurs degrades reaction time and the ability doing so, the airplane has traveled an additional 5 NM beyond to make a proper response. Best rate of climb VYSE VR / VLOF Best angle of climb VXSE Decision area Brake release Gear up and loss of one engine Figure 12-6. Area of decision for engine failure after lift-off. 12-10

Weight and Balance licensed empty weight does not. Oil must always be added to any weight and balance utilizing a licensed empty weight. The weight and balance concept is no different than that of a single-engine airplane. The actual execution, however, is When the airplane is placed in service, amended weight almost invariably more complex due to a number of new and balance documents are prepared by appropriately- loading areas, including nose and aft baggage compartments, rated maintenance personnel to reflect changes in installed nacelle lockers, main fuel tanks, auxiliary fuel tanks, nacelle equipment. The old weight and balance documents are fuel tanks, and numerous seating options in a variety of customarily marked “superseded” and retained in the AFM/ interior configurations. The flexibility in loading offered by POH. Maintenance personnel are under no regulatory the multiengine airplane places a responsibility on the pilot obligation to utilize the GAMA terminology, so weight to address weight and balance prior to each flight. and balance documents subsequent to the original may use a variety of terms. Pilots should use care to determine The terms empty weight, licensed empty weight, standard whether or not oil has to be added to the weight and balance empty weight, and basic empty weight as they appear on the calculations or if it is already included in the figures provided. manufacturer’s original weight and balance documents are sometimes confused by pilots. The multiengine airplane is where most pilots encounter the term “zero fuel weight” for the first time. Not all multiengine In 1975, the General Aviation Manufacturers Association airplanes have a zero fuel weight limitation published in (GAMA) adopted a standardized format for AFM/POHs. their AFM/POH, but many do. Zero fuel weight is simply It was implemented by most manufacturers in model year the maximum allowable weight of the airplane and payload, 1976. Airplanes whose manufacturers conform to the GAMA assuming there is no usable fuel on board. The actual airplane standards utilize the following terminology for weight and is not devoid of fuel at the time of loading, of course. This balance: is merely a calculation that assumes it was. If a zero fuel weight limitation is published, then all weight in excess of standard empty weight + optional equipment = basic empty that figure must consist of usable fuel. The purpose of a zero weight fuel weight is to limit load forces on the wing spars with heavy fuselage loads. Standard empty weight is the weight of the standard airplane, full hydraulic fluid, unusable fuel, and full oil. Optional Assume a hypothetical multiengine airplane with the equipment includes the weight of all equipment installed following weights and capacities: beyond standard. Basic empty weight is the standard empty weight plus optional equipment. Note that basic empty weight Basic empty weight . . . . . . . . . . . . . . . . . . . . . . . 3,200 lb includes no usable fuel, but full oil. Zero fuel weight . . . . . . . . . . . . . . . . . . . . . . . . . . 4,400 lb Maximum takeoff weight . . . . . . . . . . . . . . . . . . . 5,200 lb Airplanes manufactured prior to the GAMA format generally Maximum usable fuel . . . . . . . . . . . . . . . . . . . . . . . 180 gal utilize the following terminology for weight and balance, although the exact terms may vary somewhat: 1. Calculate the useful load: empty weight + unusable fuel = standard empty weight Maximum takeoff weight . . . . . . . . . . . . . . . . . . . 5,200 lb Basic empty weight . . . . . . . . . . . . . . . . . . . . . . . . –3,200 lb standard empty weight + optional equipment = licensed Useful load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2,000 lb empty weight Empty weight is the weight of the standard airplane, full The useful load is the maximum combination of usable fuel, hydraulic fluid, and undrainable oil. Unusable fuel is the fuel passengers, baggage, and cargo that the airplane is capable remaining in the airplane not available to the engines. Standard of carrying. empty weight is the empty weight plus unusable fuel. When optional equipment is added to the standard empty weight, 2. Calculate the payload: the result is licensed empty weight. Licensed empty weight, therefore, includes the standard airplane, optional equipment, Zero fuel weight . . . . . . . . . . . . . . . . . . . . . . . . . . . 4,400 lb full hydraulic fluid, unusable fuel, and undrainable oil. Basic empty weight . . . . . . . . . . . . . . . . . . . . . . . –3,200 lb Payload . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1,200 lb The major difference between the two formats (GAMA and the old) is that basic empty weight includes full oil and 12-11

The payload is the maximum combination of passengers, favorable stall characteristics. At aft CG, the airplane is baggage, and cargo that the airplane is capable of carrying. less stable, with a slightly lower stalling speed, a slightly A zero fuel weight, if published, is the limiting weight. faster cruising speed, and less desirable stall characteristics. Forward CG limits are usually determined in certification by 3. Calculate the fuel capacity at maximum payload (1,200 lb): elevator/stabilator authority in the landing roundout. Aft CG limits are determined by the minimum acceptable longitudinal Maximum takeoff weight . . . . . . . . . . . . . . . . . . . . 5,200 lb stability. It is contrary to the airplane’s operating limitations Zero fuel weight . . . . . . . . . . . . . . . . . . . . . . . . . . –4,400 lb and 14 CFR to exceed any weight and balance parameter. Fuel allowed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 800 lb Some multiengine airplanes may require ballast to remain Assuming maximum payload, the only weight permitted in within CG limits under certain loading conditions. Several excess of the zero fuel weight must consist of usable fuel. In models require ballast in the aft baggage compartment with this case, 133.3 gallons (gal). only a student and instructor on board to avoid exceeding the forward CG limit. When passengers are seated in the aft-most 4. Calculate the payload at maximum fuel capacity (180 gal): seats of some models, ballast or baggage may be required in the nose baggage compartment to avoid exceeding the aft Basic empty weight . . . . . . . . . . . . . . . . . . . . . . . . . 3,200 lb CG limit. The pilot must direct the seating of passengers and Maximum usable fuel . . . . . . . . . . . . . . . . . . . . . . +1,080 lb placement of baggage and cargo to achieve a CG within the Weight with max. fuel . . . . . . . . . . . . . . . . . . . . . . . 4,280 lb approved envelope. Most multiengine airplanes have general Maximum takeoff weight . . . . . . . . . . . . . . . . . . . . 5,200 lb loading recommendations in the weight and balance section Weight with max. fuel . . . . . . . . . . . . . . . . . . . . . . –4,280 lb of the AFM/POH. When ballast is added, it must be securely Payload allowed . . . . . . . . . . . . . . . . . . . . . . . . . . . . 920 lb tied down, and it must not exceed the maximum allowable floor loading. Assuming maximum fuel, the payload is the difference between the weight of the fueled airplane and the maximum Some airplanes make use of a special weight and balance takeoff weight. plotter. It consists of several movable parts that can be adjusted over a plotting board on which the CG envelope Some multiengine airplanes have a ramp weight, which is in is printed. The reverse side of the typical plotter contains excess of the maximum takeoff weight. The ramp weight is general loading recommendations for the particular airplane. an allowance for fuel that would be burned during taxi and A pencil line plot can be made directly on the CG envelope run-up, permitting a takeoff at full maximum takeoff weight. imprinted on the working side of the plotting board. This plot The airplane must weigh no more than maximum takeoff can easily be erased and recalculated anew for each flight. weight at the beginning of the takeoff roll. This plotter is to be used only for the make and model airplane for which it was designed. A maximum landing weight is a limitation against landing at a weight in excess of the published value. This requires Ground Operation preflight planning of fuel burn to ensure that the airplane weight upon arrival at destination is at or below the Good habits learned with single-engine airplanes are directly maximum landing weight. In the event of an emergency applicable to multiengine airplanes for preflight and engine requiring an immediate landing, the pilot should recognize start. Upon placing the airplane in motion to taxi, the new that the structural margins designed into the airplane are not multiengine pilot notices several differences, however. fully available when over landing weight. An overweight The most obvious is the increased wingspan and the need landing inspection may be advisable—the service manual for even greater vigilance while taxiing in close quarters. or manufacturer should be consulted. Ground handling may seem somewhat ponderous and the multiengine airplane is not as nimble as the typical two- or Although the foregoing problems only dealt with weight, four-place single-engine airplane. As always, use care not to the balance portion of weight and balance is equally vital. ride the brakes by keeping engine power to a minimum. One The flight characteristics of the multiengine airplane vary ground handling advantage of the multiengine airplane over significantly with shifts of the center of gravity (CG) within single-engine airplanes is the differential power capability. the approved envelope. Turning with an assist from differential power minimizes both the need for brakes during turns and the turning radius. At forward CG, the airplane is more stable, with a slightly The pilot should be aware, however, that making a sharp higher stalling speed, a slightly slower cruising speed, and turn assisted by brakes and differential power can cause the 12-12

airplane to pivot about a stationary inboard wheel and landing matched in their normal ranges. A directed and purposeful gear. This is abuse for which the airplane was not designed scan of the engine gauges can be accomplished well before and should be guarded against. Unless otherwise directed by the airplane approaches rotation speed. If a crosswind is the AFM/POH, all ground operations should be conducted present, the aileron displacement in the direction of the with the cowl flaps fully open. The use of strobe lights is crosswind may be reduced as the airplane accelerates. The normally deferred until taxiing onto the active runway. elevator/stabilator control should be held neutral throughout. Normal and Crosswind Takeoff and Climb Full rated takeoff power should be used for every takeoff. Partial power takeoffs are not recommended. There is no With the Before Takeoff checklist, which includes a pre- evidence to suggest that the life of modern reciprocating takeoff safety brief complete and air traffic control (ATC) engines is prolonged by partial power takeoffs. Paradoxically, clearance received, the airplane should be taxied into position excessive heat and engine wear can occur with partial power on the runway centerline. If departing from an airport without as the fuel metering system fails to deliver the slightly over- an operating control tower, a careful check for approaching rich mixture vital for engine cooling during takeoff. aircraft should be made along with a radio advisory on the appropriate frequency. Sharp turns onto the runway combined There are several key airspeeds to be noted during the takeoff with a rolling takeoff are not a good operating practice and and climb sequence in any twin. The first speed to consider may be prohibited by the AFM/POH due to the possibility is VMC. If an engine fails below VMC while the airplane is on of “unporting” a fuel tank pickup. (The takeoff itself may be the ground, the takeoff must be rejected. Directional control prohibited by the AFM/POH under any circumstances below can only be maintained by promptly closing both throttles and certain fuel levels.) The flight controls should be positioned using rudder and brakes as required. If an engine fails below for a crosswind, if present. Exterior lights, such as landing VMC while airborne, directional control is not possible with and taxi lights, and wingtip strobes should be illuminated the remaining engine producing takeoff power. On takeoffs, immediately prior to initiating the takeoff roll, day or night. If therefore, the airplane should never be airborne before the holding in takeoff position for any length of time, particularly airspeed reaches and exceeds VMC. Pilots should use the at night, the pilot should activate all exterior lights upon manufacturer’s recommended rotation speed (VR) or lift-off taxiing into position. speed (VLOF). If no such speeds are published, a minimum of VMC plus 5 knots should be used for VR. Takeoff power should be set as recommended in the AFM/POH. With normally aspirated (non-turbocharged) The rotation to a takeoff pitch attitude is performed with engines, this is full throttle. Full throttle is also used in most smooth control inputs. With a crosswind, the pilot should turbocharged engines. There are some turbocharged engines, ensure that the landing gear does not momentarily touch however, that require the pilot to set a specific power setting, the runway after the airplane has lifted off, as a side drift is usually just below red line manifold pressure. This yields present. The rotation may be accomplished more positively takeoff power with less than full throttle travel. Turbocharged and/or at a higher speed under these conditions. However, the engines often require special consideration. Throttle motion pilot should keep in mind that the AFM/POH performance with turbocharged engines should be exceptionally smooth figures for accelerate-stop distance, takeoff ground roll, and deliberate. It is acceptable, and may even be desirable, to and distance to clear an obstacle were calculated at the hold the airplane in position with brakes as the throttles are recommended VR and/or VLOF speed. advanced. Brake release customarily occurs after significant boost from the turbocharger is established. This prevents After lift-off, the next consideration is to gain altitude as wasting runway with slow, partial throttle acceleration as rapidly as possible. To assist the pilot in takeoff and initial the engine power is increased. If runway length or obstacle climb profile, some AFM/POHs give a “50-foot” or “50-foot clearance is critical, full power should be set before brake barrier” speed to use as a target during rotation, lift-off, and release as specified in the performance charts. acceleration to VY. Prior to takeoff, pilots should review the takeoff distance to 50 feet above ground level (AGL) As takeoff power is established, initial attention should and the stopping distance from 50 feet AGL and add the be divided between tracking the runway centerline and distance together. If the runway is no longer than the total monitoring the engine gauges. Many novice multiengine value, the odds are very good that if anything fails, it will be pilots tend to fixate on the airspeed indicator just as soon as an off-runway landing at the least. After leaving the ground, the airplane begins its takeoff roll. Instead, the pilot should altitude gain is more important than achieving an excess confirm that both engines are developing full-rated manifold of airspeed. Experience has shown that excessive speed pressure and rpm, and that as the fuel flows, fuel pressures, cannot be effectively converted into altitude in the event exhaust gas temperatures (EGTs), and oil pressures are 12-13

of an engine failure. Additional altitude increases the time power can be reduced, if desired, as the transition to en route available to recognize and respond to any aircraft abnormality climb speed is made. or emergency during the climb segment. Some airplanes have a climb power setting published in Excessive climb attitudes can be just as dangerous as the AFM/POH as a recommendation (or sometimes as a excessive airspeed. Steep climb attitudes limit forward limitation), which should then be set for en route climb. If visibility and impede the pilot’s ability to detect and avoid there is no climb power setting published, it is customary, other traffic. The airplane should be allowed to accelerate but not a requirement, to reduce manifold pressure and rpm in a shallow climb to attain VY, the best all-engine rate- somewhat for en route climb. The propellers are usually of-climb speed. VY should then be maintained until a safe synchronized after the first power reduction and the yaw single-engine maneuvering altitude, considering terrain damper, if installed, engaged. The AFM/POH may also and obstructions is achieved. Any speed above or below recommend leaning the mixtures during climb. The Climb VY reduces the performance of the airplane. Even with all checklist should be accomplished as traffic and work load engines operating normally, terrain and obstruction clearance allow. [Figure 12-7] during the initial climb after takeoff is an important preflight consideration. Most airliners and most turbine powered Level Off and Cruise airplanes climb out at an attitude that yields best rate of climb (VY) usually utilizing a flight management system (FMS). Upon leveling off at cruising altitude, the pilot should allow the airplane to accelerate at climb power until cruising When to raise the landing gear after takeoff depends on airspeed is achieved, and then cruise power and rpm should several factors. Normally, the gear should be retracted when be set. To extract the maximum cruise performance from there is insufficient runway available for landing and after any airplane, the power setting tables provided by the a positive rate of climb is established as indicated on the manufacturer should be closely followed. If the cylinder altimeter. If an excessive amount of runway is available, it head and oil temperatures are within their normal ranges, would not be prudent to leave the landing gear down for an the cowl flaps may be closed. When the engine temperatures extended period of time and sacrifice climb performance have stabilized, the mixtures may be leaned per AFM/POH and acceleration. Leaving the gear extended after the point recommendations. The remainder of the Cruise checklist at which a landing cannot be accomplished on the runway is should be completed by this point. a hazard. In some multiengine airplanes, operating in a high- density altitude environment, a positive rate of climb with Fuel management in multiengine airplanes is often more the landing gear down is not possible. Waiting for a positive complex than in single-engine airplanes. Depending upon rate of climb under these conditions is not practicable. An system design, the pilot may need to select between main important point to remember is that raising the landing gear tanks and auxiliary tanks or even employ fuel transfer from as early as possible after liftoff drastically decreases the one tank to another. In complex fuel systems, limitations are drag profile and significantly increases climb performance often found restricting the use of some tanks to level flight should an engine failure occur. An equally important point to only or requiring a reserve of fuel in the main tanks for remember is that leaving the gear down to land on sufficient descent and landing. Electric fuel pump operation can vary runway or overrun is a much better option than landing with widely among different models also, particularly during tank the gear retracted. A general recommendation is to raise the switching or fuel transfer. Some fuel pumps are to be on for landing gear not later than VYSE airspeed, and once the gear takeoff and landing; others are to be off. There is simply no is up, consider it a GO commitment if climb performance substitute for thorough systems and AFM/POH knowledge is available. Some AFM/POHs direct the pilot to apply the when operating complex aircraft. wheel brakes momentarily after lift-off to stop wheel rotation prior to landing gear retraction. If flaps were extended for Normal Approach and Landing takeoff, they should be retracted as recommended in the AFM/POH. Given the higher cruising speed (and frequently altitude) of multiengine airplanes over most single-engine airplanes, the Once a safe, single-engine maneuvering altitude has been descent must be planned in advance. A hurried, last minute reached, typically a minimum of 400—500 feet AGL, the descent with power at or near idle is inefficient and can transition to an en route climb speed should be made. cause excessive engine cooling. It may also lead to passenger This speed is higher than VY and is usually maintained to discomfort, particularly if the airplane is unpressurized. As a rule cruising altitude. En route climb speed gives better visibility, of thumb, if terrain and passenger conditions permit, a maximum increased engine cooling, and a higher groundspeed. Takeoff of a 500 fpm rate of descent should be planned. Pressurized airplanes can plan for higher descent rates, if desired. 12-14

500 feet 1. Accelerate to cruise climb 3 2. Set climb power 3. Climb checklist Positive rate–gear up Climb at VY 2 Lift-off Published VR or VLOF if not published, VMC + 5 knots 1 18 Figure 12-7. Takeoff and climb profile. In a descent, some airplanes require a minimum EGT or may for landing, tracking the extended centerline of the runway, have a minimum power setting or cylinder head temperature and established in a constant angle of descent towards an to observe. In any case, combinations of very low manifold aim point in the touchdown zone. Absent unusual flight pressure and high rpm settings are strongly discouraged by conditions, only minor corrections are required to maintain engine manufacturers. If higher descent rates are necessary, this approach to the round out and touchdown. the pilot should consider extending partial flaps or lowering the landing gear before retarding the power excessively. The The final approach should be made with power and at a Descent checklist should be initiated upon leaving cruising speed recommended by the manufacturer; if a recommended altitude and completed before arrival in the terminal area. speed is not furnished, the speed should be no slower than Upon arrival in the terminal area, pilots are encouraged to turn the single-engine best rate-of-climb speed (VYSE) until short on their landing and recognition lights when operating below final with the landing assured, but in no case less than critical 10,000 feet, day or night, and especially when operating within engine-out minimum control speed (VMC). Some multiengine 10 miles of any airport or in conditions of reduced visibility. pilots prefer to delay full flap extension to short final with the landing assured. This is an acceptable technique with The traffic pattern and approach are typically flown at appropriate experience and familiarity with the airplane. somewhat higher indicated airspeeds in a multiengine airplane contrasted to most single-engine airplanes. The In the round out for landing, residual power is gradually pilot may allow for this through an early start on the Before reduced to idle. With the higher wing loading of multiengine Landing checklist. This provides time for proper planning, airplanes and with the drag from two windmilling propellers, spacing, and thinking well ahead of the airplane. Many there is minimal float. Full stall landings are generally multiengine airplanes have partial flap extension speeds undesirable in twins. The airplane should be held off as with a above VFE, and partial flaps can be deployed prior to traffic high performance single-engine model, allowing touchdown pattern entry. Normally, the landing gear should be selected of the main wheels prior to a full stall. and confirmed down when abeam the intended point of landing as the downwind leg is flown. [Figure 12-8] Under favorable wind and runway conditions, the nosewheel can be held off for best aerodynamic braking. Even as the The FAA recommends a stabilized approach concept. To the nosewheel is gently lowered to the runway centerline, greatest extent practical, on final approach and within 500 continued elevator back pressure greatly assists the wheel feet AGL, the airplane should be on speed, in trim, configured brakes in stopping the airplane. 12-15

1 Downwind Approaching Traffic Pattern 1. Flaps–approach position 1. Descent checklist 2. Gear down 2. Reduce to traffic pattern 3. Before landing checklist airspeed and altitude 2 Base Leg 1. Gear–check down 2. Check for conflicting traffic Final 3 1. Gear–check down 2. Flaps–landing position 4 5 Amiarsnpuefaecdt–u1re.3rsVrSeOcoormmended Figure 12-8. Normal two-engine approach and landing. If runway length is critical, or with a strong crosswind, until the airplane has been brought to a halt when clear or if the surface is contaminated with water, ice or snow, of the active runway. Exceptions to this would be the rare it is undesirable to rely solely on aerodynamic braking operational needs discussed above, to relieve the weight after touchdown. The full weight of the airplane should from the wings and place it on the wheels. In these cases, be placed on the wheels as soon as practicable. The wheel AFM/POH guidance should be followed. The pilot should brakes are more effective than aerodynamic braking alone not indiscriminately reach out for any switch or control on in decelerating the airplane. landing rollout. An inadvertent landing gear retraction while meaning to retract the wing flaps may result. Once on the ground, elevator back pressure should be used to place additional weight on the main wheels and to add Crosswind Approach and Landing additional drag. When necessary, wing flap retraction also adds additional weight to the wheels and improves braking The multiengine airplane is often easier to land in a crosswind effectivity. Flap retraction during the landing rollout is than a single-engine airplane due to its higher approach discouraged, however, unless there is a clear, operational need. and landing speed. In any event, the principles are no It should not be accomplished as routine with each landing. different between singles and twins. Prior to touchdown, the longitudinal axis must be aligned with the runway centerline Some multiengine airplanes, particularly those of the to avoid landing gear side loads. cabin class variety, can be flown through the round out and touchdown with a small amount of power. This is an The two primary methods, crab and wing-low, are typically acceptable technique to prevent high sink rates and to cushion used in conjunction with each other. As soon as the airplane the touchdown. The pilot should keep in mind, however, that rolls out onto final approach, the crab angle to track the the primary purpose in landing is to get the airplane down extended runway centerline is established. This is coordinated and stopped. This technique should only be attempted when flight with adjustments to heading to compensate for wind there is a generous margin of runway length. As propeller drift either left or right. Prior to touchdown, the transition blast flows directly over the wings, lift as well as thrust is to a sideslip is made with the upwind wing lowered and produced. The pilot should taxi clear of the runway as soon opposite rudder applied to prevent a turn. The airplane as speed and safety permit, and then accomplish the After touches down on the landing gear of the upwind wing first, Landing checklist. Ordinarily, no attempt should be made followed by that of the downwind wing, and then the nose to retract the wing flaps or perform other checklist duties gear. Follow-through with the flight controls involves an 12-16

increasing application of aileron into the wind until full On short-field takeoffs in general, just after rotation and control deflection is reached. lift-off, the airplane should be allowed to accelerate to VX, making the initial climb over obstacles at VX and transitioning The point at which the transition from the crab to the sideslip is to VY as obstacles are cleared. [Figure 12-9] made is dependent upon pilot familiarity with the airplane and experience. With high skill and experience levels, the transition When partial flaps are recommended for short-field takeoffs, can be made during the round out just before touchdown. many light-twins have a strong tendency to become airborne With lesser skill and experience levels, the transition is made prior to VMC plus 5 knots. Attempting to prevent premature at increasing distances from the runway. Some multiengine lift-off with forward elevator pressure results in wheel airplanes (as some single-engine airplanes) have AFM/POH barrowing. To prevent this, allow the airplane to become limitations against slips in excess of a certain time period; 30 airborne, but only a few inches above the runway. The pilot seconds, for example. This is to prevent engine power loss from should be prepared to promptly abort the takeoff and land in fuel starvation as the fuel in the tank of the lowered wing flows the event of engine failure on takeoff with landing gear and towards the wingtip, away from the fuel pickup point. This flaps extended at airspeeds below VX. time limit must be observed if the wing-low method is utilized. Engine failure on takeoff, particularly with obstructions, is Some multiengine pilots prefer to use differential power compounded by the low airspeeds and steep climb attitudes to assist in crosswind landings. The asymmetrical thrust utilized in short-field takeoffs. VX and VXSE are often produces a yawing moment little different from that produced perilously close to VMC, leaving scant margin for error in the by the rudder. When the upwind wing is lowered, power on event of engine failure as VXSE is assumed. If flaps were used the upwind engine is increased to prevent the airplane from for takeoff, the engine failure situation becomes even more turning. This alternate technique is completely acceptable, but critical due to the additional drag incurred. If VX is less than 5 most pilots feel they can react to changing wind conditions knots higher than VMC, give strong consideration to reducing quicker with rudder and aileron than throttle movement. useful load or using another runway in order to increase the This is especially true with turbocharged engines where takeoff margins so that a short-field technique is not required. the throttle response may lag momentarily. The differential power technique should be practiced with an instructor before Short-Field Approach and Landing being attempted alone. The primary elements of a short-field approach and landing Short-Field Takeoff and Climb do not differ significantly from a normal approach and landing. Many manufacturers do not publish short-field The short-field takeoff and climb differs from the normal landing techniques or performance charts in the AFM/POH. takeoff and climb in the airspeeds and initial climb profile. In the absence of specific short-field approach and landing Some AFM/POHs give separate short-field takeoff procedures procedures, the airplane should be operated as recommended and performance charts that recommend specific flap in the AFM/POH. No operations should be conducted settings and airspeeds. Other AFM/POHs do not provide contrary to the AFM/POH recommendations. separate short-field procedures. In the absence of such specific procedures, the airplane should be operated only as The emphasis in a short-field approach is on configuration recommended in the AFM/POH. No operations should be (full flaps), a stabilized approach with a constant angle of conducted contrary to the recommendations in the AFM/POH. descent, and precise airspeed control. As part of a short- VY VY 50 feet Figure 12-9. Short-field takeoff and climb. 12-17

field approach and landing procedure, some AFM/POHs the landing gear retracted when there is a positive rate of recommend a slightly slower than normal approach airspeed. climb and no chance of runway contact. The remaining flaps If no such slower speed is published, use the AFM/POH- should then be retracted. [Figure 12-10] recommended normal approach speed. If the go-around was initiated due to conflicting traffic on the Full flaps are used to provide the steepest approach angle. ground or aloft, the pilot should maneuver to the side so as to If obstacles are present, the approach should be planned so keep the conflicting traffic in sight. This may involve a shallow that no drastic power reductions are required after they are bank turn to offset and then parallel the runway/landing area. cleared. The power should be smoothly reduced to idle in the round out prior to touchdown. Pilots should keep in mind If the airplane was in trim for the landing approach when the that the propeller blast blows over the wings providing some go-around was commenced, it soon requires a great deal of lift in addition to thrust. Reducing power significantly, just forward elevator/stabilator pressure as the airplane accelerates after obstacle clearance, usually results in a sudden, high away in a climb. The pilot should apply appropriate forward sink rate that may lead to a hard landing. After the short- pressure to maintain the desired pitch attitude. Trim should field touchdown, maximum stopping effort is achieved by be commenced immediately. The Balked Landing checklist retracting the wing flaps, adding back pressure to the elevator/ should be reviewed as work load permits. stabilator, and applying heavy braking. However, if the runway length permits, the wing flaps should be left in the Flaps should be retracted before the landing gear for two extended position until the airplane has been stopped clear reasons. First, on most airplanes, full flaps produce more drag of the runway. There is always a significant risk of retracting than the extended landing gear. Secondly, the airplane tends the landing gear instead of the wing flaps when flap retraction to settle somewhat with flap retraction, and the landing gear is attempted on the landing rollout. should be down in the event of an inadvertent, momentary touchdown. Landing conditions that involve a short-field, high-winds, or strong crosswinds are just about the only situations where Many multiengine airplanes have a landing gear retraction flap retraction on the landing rollout should be considered. speed significantly less than the extension speed. Care should When there is an operational need to retract the flaps just be exercised during the go-around not to exceed the retraction after touchdown, it must be done deliberately with the flap speed. If the pilot desires to return for a landing, it is essential handle positively identified before it is moved. to re-accomplish the entire Before Landing checklist. An interruption to a pilot’s habit patterns, such as a go-around, Go-Around is a classic scenario for a subsequent gear up landing. When the decision to go around is made, the throttles should The preceding discussion about doing a go-around assumes be advanced to takeoff power. With adequate airspeed, the that the maneuver was initiated from normal approach speeds airplane should be placed in a climb pitch attitude. These or faster. If the go-around was initiated from a low airspeed, actions, which are accomplished simultaneously, arrest the the initial pitch up to a climb attitude must be tempered with sink rate and place the airplane in the proper attitude for the necessity of maintaining adequate flying speed throughout transition to a climb. The initial target airspeed is VY or VX the maneuver. Examples of where this applies include a if obstructions are present. With sufficient airspeed, the flaps go-around initiated from the landing round out or recovery should be retracted from full to an intermediate position and Positive rate Retract remaining 500' of climb, retract flaps Cruise climb Timely decision to Apply max power gear, climb make go-around adjust pitch attitude at VY to arrest sink rate Flaps to intermediate Figure 12-10. Go-around procedure. 12-18

from a bad bounce, as well as a go-around initiated due to drag and yawing tendency. Airplane climb performance is an inadvertent approach to a stall. The first priority is always marginal or even non-existent, and obstructions may lie ahead. to maintain control and obtain adequate flying speed. A few An emergency contingency plan and safety brief should be moments of level or near level flight may be required as the clearly understood well before the takeoff roll commences. airplane accelerates up to climb speed. An engine failure before a predetermined airspeed or point results in an aborted takeoff. An engine failure after a certain Rejected Takeoff airspeed and point, with the gear up, and climb performance assured result in a continued takeoff. With loss of an engine, A takeoff can be rejected for the same reasons a takeoff in a it is paramount to maintain airplane control and comply with single-engine airplane would be rejected. Once the decision to the manufacturer’s recommended emergency procedures. reject a takeoff is made, the pilot should promptly close both Complete failure of one engine shortly after takeoff can be throttles and maintain directional control with the rudder, broadly categorized into one of three following scenarios. nosewheel steering, and brakes. Aggressive use of rudder, nosewheel steering, and brakes may be required to keep the Landing Gear Down airplane on the runway. Particularly, if an engine failure is If the engine failure occurs prior to selecting the landing gear not immediately recognized and accompanied by prompt to the UP position [Figure 12-11]: Keep the nose as straight closure of both throttles. However, the primary objective is as possible, close both throttles, allow the nose to maintain not necessarily to stop the airplane in the shortest distance, but airspeed and descend to the runway. Concentrate on a normal to maintain control of the airplane as it decelerates. In some landing and do not force the aircraft on the ground. Land situations, it may be preferable to continue into the overrun on the remaining runway or overrun. Depending upon how area under control, rather than risk directional control loss, quickly the pilot reacts to the sudden yaw, the airplane may landing gear collapse, or tire/brake failure in an attempt to run off the side of the runway by the time action is taken. stop the airplane in the shortest possible distance. There are really no other practical options. As discussed earlier, the chances of maintaining directional control while Engine Failure After Lift-Off retracting the flaps (if extended), landing gear, feathering the propeller, and accelerating are minimal. On some airplanes A takeoff or go-around is the most critical time to suffer with a single-engine-driven hydraulic pump, failure of that an engine failure. The airplane will be slow, close to the engine means the only way to raise the landing gear is to ground, and may even have landing gear and flaps extended. allow the engine to windmill or to use a hand pump. This is Altitude and time is minimal. Until feathered, the propeller not a viable alternative during takeoff. of the failed engine is windmilling, producing a great deal of 18 1 If engine failure occurs at or before lift-off, abort the takeoff If failure of engine occurs after lift-off: 1. Maintain directional control 2. Close both throttles 2 Figure 12-11. Engine failure on takeoff, landing gear down. 12-19

Engine failure laDnedsucenndderactoVnYtSrEol on or off runway Liftoff Over run area Figure 12-12. Engine failure on takeoff, inadequate climb performance. Landing Gear Control Selected Up, Single-Engine As mentioned previously, if the airplane’s landing gear Climb Performance Inadequate retraction mechanism is dependent upon hydraulic pressure When operating near or above the single-engine ceiling and from a certain engine-driven pump, failure of that engine can an engine failure is experienced shortly after lift-off, a landing mean a loss of hundreds of feet of altitude as the pilot either must be accomplished on whatever essentially lies ahead. windmills the engine to provide hydraulic pressure to raise [Figure 12-12] There is also the option of continuing ahead, in the gear or raises it manually with a backup pump. a descent at VYSE with the remaining engine producing power, as long as the pilot is not tempted to remain airborne beyond Landing Gear Control Selected Up, Single-Engine the airplane’s performance capability. Remaining airborne Climb Performance Adequate and bleeding off airspeed in a futile attempt to maintain If the single-engine rate of climb is adequate, the procedures altitude is almost invariably fatal. Landing under control is for continued flight should be followed. [Figure 12-13] There paramount. The greatest hazard in a single-engine takeoff are four areas of concern: control, configuration, climb, and is attempting to fly when it is not within the performance checklist. capability of the airplane to do so. An accident is inevitable. Control Analysis of engine failures on takeoff reveals a very high The first consideration following engine failure during takeoff success rate of off-airport engine inoperative landings when the is to maintain control of the airplane. Maintaining directional airplane is landed under control. Analysis also reveals a very control with prompt and often aggressive rudder application high fatality rate in stall spin accidents when the pilot attempts and STOPPING THE YAW is critical to the safety of flight. flight beyond the performance capability of the airplane. Ensure that airspeed stays above VMC. If the yaw cannot be controlled with full rudder applied, reducing thrust on the Obstruction Clearance Altitude or Above 1 3. Drag–reduce - gear, flaps 4. Identify–inoperative engine If failure of engine occurs after liftoff: 5. Verify–inoperative engine 1. Maintain dbiarencktiionntoalocpoenratrtoinl–gVeYnSEg,ine 2 6. Feather–inoperative engine heading, 2. Power–increase or set for takeoff 3 At 500' or obstruction clearance altitude: 7. Engine failure checklist circle and land Figure 12-13. Landing gear up—adequate climb performance. 12-20

operative engine is the only alternative. Attempting to correct when the suspected throttle is retarded is verification the roll with aileron without first applying rudder increases that the correct engine has been identified as failed. The drag and adverse yaw and further degrades directional corresponding propeller control should be brought fully aft control. After rudder is applied to stop the yaw, a slight to feather the engine. amount of aileron should be used to bank the airplane toward the operative engine. This is the most efficient way to control Climb the aircraft, minimize drag, and gain the most performance. As soon as directional control is established and the airplane Control forces, particularly on the rudder, may be high. The configured for climb, the bank angle should be reduced to that pitch attitude for VYSE has to be lowered from that of VY. At producing best climb performance. Without specific guidance least 5° of bank should be used initially to stop the yaw and for zero sideslip, a bank of 2° and one-third to one-half ball maintain directional control. This initial bank input is held deflection on the slip/skid indicator is suggested. VYSE is only momentarily, just long enough to establish or ensure maintained with pitch control. As turning flight reduces climb directional control. Climb performance suffers when bank performance, climb should be made straight ahead or with angles exceed approximately 2 or 3°, but obtaining and shallow turns to avoid obstacles to an altitude of at least 400 maintaining VYSE and directional control are paramount. Trim feet AGL before attempting a return to the airport. should be adjusted to lower the control forces. Checklist Configuration Having accomplished the memory items from the Engine The memory items from the Engine Failure After Takeoff Failure After Takeoff checklist, the printed copy should checklist should be promptly executed to configure the be reviewed as time permits. The Securing Failed Engine airplane for climb. [Figure 12-14] The specific procedures checklist should then be accomplished. [Figure 12-15] Unless to follow are found in the AFM/POH and checklist for the the pilot suspects an engine fire, the remaining items should particular airplane. Most direct the pilot to assume VYSE, set be accomplished deliberately and without undue haste. takeoff power, retract the flaps and landing gear, identify, Airplane control should never be sacrificed to execute the verify, and feather the failed engine. (On some airplanes, the remaining checklists. The priority items have already been landing gear is to be retracted before the flaps.) accomplished from memory. The “identify” step is for the pilot to initially identify the Other than closing the cowl flap of the failed engine, none of failed engine. Confirmation on the engine gauges may or these items, if left undone, adversely affects airplane climb may not be possible, depending upon the failure mode. performance. There is a distinct possibility of actuating an Identification should be primarily through the control inputs incorrect switch or control if the procedure is rushed. The required to maintain straight flight, not the engine gauges. pilot should concentrate on flying the airplane and extracting The “verify” step directs the pilot to retard the throttle of the maximum performance. If an ATC facility is available, an engine thought to have failed. No change in performance emergency should be declared. Engine Failure After Takeoff The memory items in the Engine Failure After Takeoff Airspeed .............................................................Maintain VYSE checklist may be redundant with the airplane’s existing Mixtures........................................................................... RICH configuration. For example, in the third takeoff scenario, Propellers.............................................................. HIGH RPM the gear and flaps were assumed to already be retracted, Throttles ........................................................... FULL POWER yet the memory items included gear and flaps. This is not Flaps .................................................................................... UP an oversight. The purpose of the memory items is to either Landing gear....................................................................... UP initiate the appropriate action or to confirm that a condition Identify............................................. Determine failed engine exists. Action on each item may not be required in all cases. Verify......................................Close throttle of failed engine The memory items also apply to more than one circumstance. Propeller.................................................................. FEATHER In an engine failure from a go-around, for example, the Trim tabs...................................................................... ADJUST landing gear and flaps would likely be extended when the Failed engine.............................................................. SECURE failure occurred. As soon as practical.........................................................LAND Bold-faced items require immediate action and are to be The three preceding takeoff scenarios all include the landing accomplished from memory. gear as a key element in the decision to land or continue. With the landing gear selector in the DOWN position, for Figure 12-14. Typical “engine failure after takeoff” emergency example, continued takeoff and climb is not recommended. This situation, however, is not justification to retract the checklist. 12-21

Securing Failed Engine the failure. Maintaining airplane control, however, is still Mixture............................................................... IDLE CUT OFF paramount. Airplanes have been lost at altitude due to Magnetos ........................................................................... OFF apparent fixation on the engine problem to the detriment of Alternator............................................................................ OFF flying the airplane. Cowl flap ....................................................................... CLOSE Boost pump ....................................................................... OFF Not all engine failures or malfunctions are catastrophic in Fuel selector....................................................................... OFF nature (catastrophic meaning a major mechanical failure that Prop sync ........................................................................... OFF damages the engine and precludes further engine operation). Electrical load................................................................Reduce Many cases of power loss are related to fuel starvation, Crossfeed................................................................... Consider where restoration of power may be made with the selection of another tank. An orderly inventory of gauges and switches Figure 12-15. Typical “securing failed engine” emergency checklist. may reveal the problem. Carburetor heat or alternate air can be selected. The affected engine may run smoothly on landing gear the moment the airplane lifts off the surface just one magneto or at a lower power setting. Altering the on takeoff as a normal procedure. The landing gear should mixture may help. If fuel vapor formation is suspected, fuel remain selected down as long as there is usable runway or boost pump operation may be used to eliminate flow and overrun available to land on. The use of wing flaps for takeoff pressure fluctuations. virtually eliminates the likelihood of a single-engine climb until the flaps are retracted. Although it is a natural desire among pilots to save an ailing engine with a precautionary shutdown, the engine should be There are two time-tested memory aids the pilot may find left running if there is any doubt as to needing it for further useful in dealing with engine-out scenarios. The first, “dead safe flight. Catastrophic failure accompanied by heavy foot—dead engine” is used to assist in identifying the failed vibration, smoke, blistering paint, or large trails of oil, on engine. Depending on the failure mode, the pilot will not the other hand, indicate a critical situation. The affected be able to consistently identify the failed engine in a timely engine should be feathered and the Securing Failed Engine manner from the engine gauges. In maintaining directional checklist completed. The pilot should divert to the nearest control, however, rudder pressure is exerted on the side (left suitable airport and declare an emergency with ATC for or right) of the airplane with the operating engine. Thus, priority handling. the “dead foot” is on the same side as the “dead engine.” Variations on this saying include “idle foot—idle engine” Fuel crossfeed is a method of getting fuel from a tank on and “working foot–working engine.” one side of the airplane to an operating engine on the other. Crossfeed is used for extended single-engine operation. The second memory aid has to do with climb performance. If a suitable airport is close at hand, there is no need to The phrase “raise the dead” is a reminder that the best climb consider crossfeed. If prolonged flight on a single-engine performance is obtained with a very shallow bank, about 2° is inevitable due to airport non-availability, then crossfeed toward the operating engine. Therefore, the inoperative, or allows use of fuel that would otherwise be unavailable to “dead” engine should be “raised” with a very slight bank. the operating engine. It also permits the pilot to balance the fuel consumption to avoid an out-of-balance wing heaviness. Not all engine power losses are complete failures. Sometimes The AFM/POH procedures for crossfeed vary widely. the failure mode is such that partial power may be available. Thorough fuel system knowledge is essential if crossfeed If there is a performance loss when the throttle of the affected is to be conducted. Fuel selector positions and fuel boost engine is retarded, the pilot should consider allowing it to run pump usage for crossfeed differ greatly among multiengine until altitude and airspeed permit safe single-engine flight, airplanes. Prior to landing, crossfeed should be terminated if this can be done without compromising safety. Attempts and the operating engine returned to its main tank fuel supply. to save a malfunctioning engine can lead to a loss of the entire airplane. If the airplane is above its single-engine absolute ceiling at the time of engine failure, it slowly loses altitude. The pilot Engine Failure During Flight should maintain VYSE to minimize the rate of altitude loss. This “drift down” rate is greatest immediately following Engine failures well above the ground are handled differently the failure and decreases as the single-engine ceiling is than those occurring at lower speeds and altitudes. Cruise approached. Due to performance variations caused by airspeed allows better airplane control and altitude, which engine and propeller wear, turbulence, and pilot technique, may permit time for a possible diagnosis and remedy of 12-22

the airplane may not maintain altitude even at its published round out just prior to touchdown. With drag from only one single-engine ceiling. Any further rate of sink, however, windmilling propeller, the airplane tends to float more than would likely be modest. on a two-engine approach. Precise airspeed control therefore is essential, especially when landing on a short, wet, and/or An engine failure in a descent or other low power setting slippery surface. can be deceiving. The dramatic yaw and performance loss is absent. At very low power settings, the pilot may not Some pilots favor resetting the rudder trim to neutral on final even be aware of a failure. If a failure is suspected, the pilot and compensating for yaw by holding rudder pressure for the should advance both engine mixtures, propellers, and throttles remainder of the approach. This eliminates the rudder trim significantly, to the takeoff settings if necessary, to correctly change close to the ground as the throttle is closed during identify the failed engine. The power on the operative engine the round out for landing. This technique eliminates the can always be reduced later. need for groping for the rudder trim and manipulating it to neutral during final approach, which many pilots find to be Engine Inoperative Approach and Landing highly distracting. AFM/POH recommendations or personal preference should be used. The approach and landing with OEI is essentially the same as a two-engine approach and landing. The traffic pattern A single-engine go-around must be avoided. As a practical should be flown at similar altitudes, airspeeds, and key matter in single-engine approaches, once the airplane is on positions as a two-engine approach. The differences are final approach with landing gear and flaps extended, it is the reduced power available and the fact that the remaining committed to land on the intended runway, on another runway, thrust is asymmetrical. A higher-than-normal power setting a taxiway, or grassy infield. The light-twin does not have the is necessary on the operative engine. performance to climb on one engine with landing gear and flaps extended. Considerable altitude is lost while maintaining With adequate airspeed and performance, the landing gear VYSE and retracting landing gear and flaps. Losses of 500 feet can still be extended on the downwind leg. In which case it or more are not unusual. If the landing gear has been lowered should be confirmed DOWN no later than abeam the intended with an alternate means of extension, retraction may not be point of landing. Performance permitting, initial extension of possible, virtually negating any climb capability. wing flaps (typically 10°) and a descent from pattern altitude can also be initiated on the downwind leg. The airspeed Engine Inoperative Flight Principles should be no slower than VYSE. The direction of the traffic pattern, and therefore the turns, is of no consequence as far as Best single-engine climb performance is obtained at VYSE airplane controllability and performance are concerned. It is with maximum available power and minimum drag. After the perfectly acceptable to make turns toward the failed engine. flaps and landing gear have been retracted and the propeller of the failed engine feathered, a key element in best climb On the base leg, if performance is adequate, the flaps may performance is minimizing sideslip. be extended to an intermediate setting (typically 25°). If the performance is inadequate, as measured by decay in airspeed With a single-engine airplane or a multiengine airplane with or high sink rate, delay further flap extension until closer to both engines operative, sideslip is eliminated when the ball of the runway. VYSE is still the minimum airspeed to maintain. the turn and bank instrument is centered. This is a condition of zero sideslip, and the airplane is presenting its smallest On final approach, a normal, 3° glidepath to a landing is possible profile to the relative wind. As a result, drag is at its desirable. Visual approach slope indicator (VASI) or other minimum. Pilots know this as coordinated flight. vertical path lighting aids should be utilized if available. Slightly steeper approaches may be acceptable. However, a In a multiengine airplane with an inoperative engine, the long, flat, low approach should be avoided. Large, sudden centered ball is no longer the indicator of zero sideslip due power applications or reductions should also be avoided. to asymmetrical thrust. In fact, there is no instrument at Maintain VYSE until the landing is assured, then slow to 1.3 all that directly tells the pilot the flight conditions for zero VSO or the AFM/POH recommended speed. The final flap sideslip. In the absence of a yaw string, minimizing sideslip setting may be delayed until the landing is assured or the is a matter of placing the airplane at a predetermined bank airplane may be landed with partial flaps. angle and ball position. The AFM/POH performance charts for single-engine flight were determined at zero sideslip. If The airplane should remain in trim throughout. The pilot this performance is even to be approximated, the zero sideslip must be prepared, however, for a rudder trim change as technique must be utilized. the power of the operating engine is reduced to idle in the 12-23

There are two different control inputs that can be used to Relative wind Yaw counteract the asymmetrical thrust of a failed engine: string 1. Yaw from the rudder Thrust 2. The horizontal component of lift that results from bank with the ailerons. Used individually, neither is correct. Used together in the Drag proper combination, zero sideslip and best climb performance are achieved. Slipstream Three different scenarios of airplane control inputs are Fin effect due presented below. Neither of the first two is correct. They to sideslip are presented to illustrate the reasons for the zero sideslip approach to best climb performance. Rudder force 1. Engine inoperative flight with wings level and ball NAV1 108.00 113.00 WPT _ _ _ _ _ _ DIS _ _ ._ NM DTK _ _ _° TRK 360° 134.000 118.000 COM1 centered requires large rudder input towards the NAV2 108.00 110.60 123.800 118.000 COM2 operative engine. [Figure 12-16] The result is a moderate sideslip towards the inoperative engine. 130 44030000 2 Climb performance is reduced by the moderate sideslip. 4200 With wings level, VMC is significantly higher than 120 published as there is no horizontal component of lift 270° 4100 1 available to help the rudder combat asymmetrical thrust. 1110 VOR 1 60 100 1 2. Engine inoperative flight using ailerons alone requires 44000000 2 an 8–10° bank angle towards the operative engine. 9 20 [Figure 12-17] This assumes no rudder input. The 90 3900 ball is displaced well towards the operative engine. The result is a large sideslip towards the operative 80 3800 engine. Climb performance is greatly reduced by the large sideslip. 70TAS 106KT 4300 3. Rudder and ailerons used together in the proper OAT 7°C 3600 combination result in a bank of approximately 2° towards the operative engine. The ball is displaced 3500 approximately one-third to one-half towards the operative engine. The result is zero sideslip and Wings level, ball centered, airplane slips toward3400 dead engine. maximum climb performance. [Figure 12-18] Any Results: high large control surface 3300 required,10:12:34 attitude other than zero sideslip increases drag, drag, deflections3X2P0D0R 5537 IDNT LCL decreasing performance. VMC under these circumstances ALERTS is higher than published, as less than the 5° bank and rudder and fin in opposition due to side310s0 lip. certification limit is employed. Figure 12-16. Wings level engine-out flight. The precise condition of zero sideslip (bank angle and ball position) varies slightly from model to model and with When bank angle is plotted against climb performance for a available power and airspeed. If the airplane is not equipped hypothetical twin, zero sideslip results in the best (however with counter-rotating propellers, it also varies slightly with marginal) climb performance or the least rate of descent. the engine failed due to P-factor. The foregoing zero sideslip Zero bank (all rudder to counteract yaw) degrades climb recommendations apply to reciprocating engine multiengine performance as a result of moderate sideslip. Using bank airplanes flown at VYSE with the inoperative engine feathered. angle alone (no rudder) severely degrades climb performance The zero sideslip ball position for straight flight is also the as a result of a large sideslip. zero sideslip position for turning flight. The actual bank angle for zero sideslip varies among airplanes from one and one-half to two and one-half degrees. The position of the ball varies from one-third to one-half of a ball width from instrument center. 12-24

Yaw Relative wind Relative wind string Thrust Yaw string Thrust Drag Drag Rudder force NAV1 108.00 113.00 WPT _ _ _ _ _ _ DIS _ _ ._ NM DTK _ _ _° TRK 360° 134.000 118.000 COM1 NAV2 108.00 110.60 123.800 118.000 COM2 130 44030000 2 4200 120 4100 1 NAV1 108.00 113.00 WPT _ _ _ _ _ _ DIS _ _ ._ NM DTK _ _ _° TRK 360° 134.000 118.000 COM1 1110 60 NAV2 108.00 110.60 123.800 118.000 COM2 100 1 270° 44000000 2 130 44030000 9 VOR 1 20 4200 90 3900 120 2 80 3800 1110 100 70 4300 9 TAS 106KT 3600 90 OAT 7°C 80 3500 4100 1 70TAS 106KT 60 Excess bank toward operating engine, no rudder3400 input. 1 3300 OAT 7°C 44000000 2 Result: large sideslip toward operating engine3X2P0D0R 5537 and greatlyIDNT LCL 20 ALERTS 10:12:34 270° 3900 VOR 1 3100 3800 4300 reduced climb performance. 3600 3500 Bank toward operating engine, no sideslip. 3400 3300 Figure 12-17. Excessive bank engine-out flight. Results: much lower drag and smaller control surface3X2P0D0R 5537 IDNT LCL 10:12:34 ALERTS deflections. 3100 For any multiengine airplane, zero sideslip can be confirmed Figure 12-18. Zero sideslip engine-out flight. through the use of a yaw string. A yaw string is a piece of string or yarn approximately 18 to 36 inches in length taped to the remaining engine reveals the precise bank angle and the base of the windshield or to the nose near the windshield ball deflection required for zero sideslip and best climb along the airplane centerline. In two-engine coordinated performance. Zero sideslip is again indicated by the yaw flight, the relative wind causes the string to align itself with string when it aligns itself vertically on the windshield. There the longitudinal axis of the airplane, and it positions itself are very minor changes from this attitude depending upon the straight up the center of the windshield. This is zero sideslip. engine failed (with non-counter-rotating propellers), power Experimentation with slips and skids vividly displays the available, airspeed and weight; but without more sensitive location of the relative wind. Adequate altitude and flying speed testing equipment, these changes are difficult to detect. must be maintained while accomplishing these maneuvers. The only significant difference would be the pitch attitude required to maintain VYSE under different density altitude, With an engine set to zero thrust (or feathered) and the power available, and weight conditions. airplane slowed to VYSE, a climb with maximum power on 12-25

If a yaw string is attached to the airplane at the time of a VMC multiengine airplanes tend to heat up fairly quickly under demonstration, it is noted that VMC occurs under conditions some conditions of slow flight, particularly in the landing of sideslip. VMC was not determined under conditions of zero configuration. Simulated engine failures should not be sideslip during aircraft certification and zero sideslip is not conducted during slow flight. The airplane will be well below part of a VMC demonstration for pilot certification. VSSE and very close to VMC. Stability, stall warning, or stall avoidance devices should not be disabled while maneuvering To review, there are two different sets of bank angles used during slow flight. in OEI flight. Stalls 1. To maintain directional control of a multiengine airplane suffering an engine failure at low speeds Stall characteristics vary among multiengine airplanes just (such as climb), momentarily bank at least 5° and a as they do with single-engine airplanes, and therefore, a maximum of 10° towards the operative engine as the pilot must be familiar with them. Yet, the most important pitch attitude for VYSE is set. This maneuver should be stall recovery step in a multiengine airplane is the same as instinctive to the proficient multiengine pilot and take it is in all airplanes: reduce the angle of attack (AOA). For only 1 to 2 seconds to attain. It is held just long enough reference, the stall recovery procedure described in Chapter to assure directional control as the pitch attitude for 4 is included in Figure 12-19. VYSE is assumed. Following a reduction in the AOA and the stall warning being 2. To obtain the best climb performance, the airplane eliminated, the wings should be rolled level and power added must be flown at VYSE and zero sideslip with the failed as needed. Immediate full application of power in a stalled engine feathered and maximum available power from condition has an associated risk due to the possibility of the operating engine. Zero sideslip is approximately 2° asymmetric thrust. In addition, single-engine stalls or stalls of bank toward the operating engine and a one-third with significantly more power on one engine than the other to one-half ball deflection also toward the operating should not be attempted due to the likelihood of a departure engine. The precise bank angle and ball position varies from controlled flight and possible spin entry. Similarly, somewhat with make and model and power available. If simulated engine failures should not be performed during above the airplane’s single-engine ceiling, this attitude stall entry and recovery. and configuration results in the minimum rate of sink. In OEI flight at low altitudes and airspeeds such as the It is recommended that stalls be practiced at an altitude initial climb after takeoff, pilots must operate the airplane that allows recovery no lower than 3,000 feet AGL for so as to guard against the three major accident factors: (1) multiengine airplanes, or higher if recommended by the loss of directional control, (2) loss of performance, and (3) AFM/POH. Losing altitude during recovery from a stall is loss of flying speed. All have equal potential to be lethal. to be expected. Loss of flying speed is not a factor, however, when the airplane is operated with due regard for directional control Power-Off Approach to Stall (Approach and and performance. Landing) A power-off approach to stall is trained and checked to Slow Flight simulate problematic approach and landing scenarios. A power-off approach to stall may be performed with wings There is nothing unusual about maneuvering during slow level, or from shallow and medium banked turns (20 degrees flight in a multiengine airplane. Slow flight may be conducted of bank). To initiate a power-off approach to stall maneuver, in straight-and-level flight, turns, climbs, or descents. It the area surrounding the airplane should first be cleared for can also be conducted in the clean configuration, landing possible traffic. The airplane should then be slowed and configuration, or at any other combination of landing gear configured for an approach and landing. A stabilized descent and flaps. Slow flight in a multiengine airplane should be should be established (approximately 500 fpm) and trim conducted so the maneuver can be completed no lower adjusted. A turn should be initiated at this point, if desired. than 3,000 feet AGL or higher if recommended by the The pilot should then smoothly increase the AOA to induce manufacturer. In all cases, practicing slow flight should a stall warning. Power is reduced further during this phase, be conducted at an adequate height above the ground for and trimming should cease at speeds slower than takeoff. recovery should the airplane inadvertently stall. When the airplane reaches the stall warning (e.g., aural alert, Pilots should closely monitor cylinder head and oil buffet, etc.), the recovery is accomplished by first reducing temperatures during slow flight. Some high performance 12-26

1. Wing leveler or autopilot Stall Recovery Template 2. a) Nose-down pitch control 1. Disconnect b) Nose-down pitch trim 2. a) Apply until impending stall indications are eliminated 3. Bank 4. Thrust/Power b) As needed 5. Speed brakes/spoilers 3. Wings Level 6. Return to the desired flight path 4. As needed 5. Retract Figure 12-19. Stall recovery procedure. the AOA until the stall warning is eliminated. The pilot then be retracted when a positive rate of climb is attained, and flaps rolls the wings level with coordinated use of the rudder and retracted, if flaps were set for takeoff. The target airspeed on smoothly applies power as required. The airplane should be recovery is VX if (simulated) obstructions are present, or VY. accelerated to VX (if simulated obstacles are present) or VY The pilot should anticipate the need for nose-down trim as the during recovery and climb. Considerable forward elevator/ airplane accelerates to VX or VY after recovery. stabilator pressure will be required after the stall recovery as the airplane accelerates to VX or VY. Appropriate trim Full Stall input should be anticipated. The flap setting should be It is not recommended that full stalls be practiced unless a reduced from full to approach, or as recommended by the qualified flight instructor is present. A power-off or power-on manufacturer. Then, with a positive rate of climb, the landing full stall should only be practiced in a structured lesson with gear is selected up. The remaining flaps are then retracted as clear learning objectives and cautions discussed. The goals a positive rate-of-climb continues. of the training are (a) to provide the pilots the experience of the handling characteristics and dynamic cues (e.g., Power-On Approach to Stall (Takeoff and Departure) buffet, roll off) near and at full stall and (b) to reinforce the A power-on approach to stall is trained and checked to proper application of the stall recovery procedures. Given simulate problematic takeoff scenarios. A power-on approach the associated risk of asymmetric thrust at high angles of to stall may be performed from straight-and-level flight attack and low rudder effectiveness due to low airspeeds, or from shallow and medium banked turns (20 degrees of this reinforces the primary step of first lowering the AOA, bank). To initiate a power-on approach to stall maneuver, which allows all control surfaces to become more effective the area surrounding the airplane should always be cleared and allows for roll to be better controlled. Thrust should only to look for potential traffic. The airplane is slowed to the be used as needed in the recovery. manufacturer’s recommended lift-off speed. The airplane should be configured in the takeoff configuration. Trim should Accelerated Approach to Stall be adjusted for this speed. Engine power is then increased Accelerated approach to stall should be performed with a bank to that recommended in the AFM/POH for the practice of of approximately 45°, and in no case at a speed greater than power-on approach to stall. In the absence of a recommended the airplane manufacturer’s recommended airspeed or the setting, use approximately 65 percent of maximum available specified design maneuvering speed (VA). The entry altitude power. Begin a turn, if desired, while increasing AOA to for this maneuver should be no lower than 5,000 feet AGL. induce a stall warning (e.g., aural alert, buffet, etc.). Other specified (reduced) power settings may be used to simulate The entry method for the maneuver is no different than performance at higher gross weights and density altitudes. for a single-engine airplane. Once at an appropriate speed, begin increasing the back pressure on the elevator while When the airplane reaches the stall warning, the recovery maintaining a coordinated 45° turn. A good speed reduction is made first by reducing the AOA until the stall warning is rate is approximately 3-5 knots per second. Once a stall eliminated. The pilot then rolls the wings level with coordinated warning occurs, recover promptly by reducing the AOA use of the rudder and applying power as needed. However, until the stall warning stops. Then roll the wings level with if simulating limited power available for high gross weight coordinated rudder and add power as necessary to return to and density altitude situations, the power during the recovery the desired flightpath. should be limited to that specified. The landing gear should 12-27

Spin Awareness As very few twins have ever been spin-tested (none are No multiengine airplane is approved for spins, and their spin required to), the recommended spin recovery techniques recovery characteristics are generally very poor. It is therefore are based only on the best information available. The necessary to practice spin avoidance and maintain a high departure from controlled flight may be quite abrupt and awareness of situations that can result in an inadvertent spin. possibly disorienting. The direction of an upright spin can be confirmed from the turn needle or the symbolic airplane In order to spin any airplane, it must first be stalled. At the of the turn coordinator, if necessary. Do not rely on the ball stall, a yawing moment must be introduced. In a multiengine position or other instruments. airplane, the yawing moment may be generated by rudder input or asymmetrical thrust. It follows, then, that spin If a spin is entered, most manufacturers recommend awareness be at its greatest during VMC demonstrations, stall immediately retarding both throttles to idle, applying full practice, slow flight, or any condition of high asymmetrical rudder opposite the direction of rotation, and applying full thrust, particularly at low speed/high AOA. Single-engine forward elevator/stabilator pressure (with ailerons neutral). stalls are not part of any multiengine training curriculum. These actions should be taken as near simultaneously as possible. The controls should then be held in that position No engine failure should ever be introduced below safe, until the spin has stopped. At that point adjust rudder pressure, intentional one-engine inoperative speed (VSSE). If no VSSE back elevator pressure, and power as necessary to return to is published, use VYSE. Other than training situations, the the desired flight path. Pilots should be aware that a spin multiengine airplane is only operated below VSSE for mere recovery will take considerable altitude therefore it is critical seconds just after lift-off or during the last few dozen feet of that corrective action be taken immediately. altitude in preparation for landing. For spin avoidance when practicing engine failures, the flight instructor should pay strict attention to the maintenance of proper airspeed and bank angle as the student executes the appropriate procedure. The instructor should also be particularly alert during stall and slow flight practice. Forward center-of-gravity positions result in favorable stall and spin avoidance characteristics, but do not eliminate the hazard. When performing a VMC demonstration, the instructor should also be alert for any sign of an impending stall. The student may be highly focused on the directional control aspect of the maneuver to the extent that impending stall indications go unnoticed. If a VMC demonstration cannot be accomplished under existing conditions of density altitude, it may, for training purposes, be done utilizing the rudder blocking technique described in the following section. 12-28

CTharptear13nsition to Tailwheel Airplanes Introduction Due to their design and structure, tailwheel airplanes (tailwheels) exhibit operational and handling characteristics different from those of tricycle-gear airplanes (nosewheels). [Figure 13-1] In general, tailwheels are less forgiving of pilot error while in contact with the ground than are nosewheels. This chapter focuses on the operational differences that occur during ground operations, takeoffs, and landings. Although still termed “conventional-gear airplanes,” tailwheel designs are most likely to be encountered today by pilots who have first learned in nosewheels. Therefore, tailwheel operations are approached as they appear to a pilot making a transition from nosewheel designs. 13-1

Figure 13-1. The Piper Super Cub on the left is a popular tailwheel airplane. The airplane on the right is a Mooney M20, which is a nosewheel (tricycle gear) airplane. Landing Gear stop a turn that has been started, and it is necessary to apply an opposite input (opposite rudder) to bring the aircraft back The main landing gear forms the principal support of the to straight-line travel. airplane on the ground. The tailwheel also supports the airplane, but steering and directional control are its primary If the initial rudder input is maintained after a turn has been functions. With the tailwheel-type airplane, the two main struts started, the turn continues to tighten, an unexpected result are attached to the airplane slightly ahead of the airplane’s for pilots accustomed to a nosewheel. In consequence, it is center of gravity (CG), so that the plane naturally rests in a common for pilots making the transition between the two nose-high attitude on the triangle created by the main gear and types to experience difficulty in early taxi attempts. As long the tailwheel. This arrangement is responsible for the three as taxi speeds are kept low, however, no serious problems major handling differences between nosewheel and tailwheel result, and pilots typically adjust quickly to the technique of airplanes. They center on directional instability, angle of attack using rudder pressure to start a turn, then neutralizing the (AOA), and crosswind weathervaning tendencies. pedals as the turn continues, and finally using an opposite pedal input to stop the turn and regain straight line travel. Proper usage of the rudder pedals is crucial for directional control while taxiing. Steering with the pedals may be Because of this inbuilt instability, the most important lesson accomplished through the forces of airflow or propeller that can be taught in tailwheel airplanes is to taxi and make slipstream acting on the rudder surface or through a turns at slow speeds. mechanical linkage acting through springs to communicate steering inputs to the tailwheel. Initially, the pilot should taxi Angle of Attack with the heels of the feet resting on the floor and the balls of the feet on the bottom of the rudder pedals. The feet should A second strong contrast to nosewheel airplanes, tailwheel be slid up onto the brake pedals only when it is necessary to aircraft make lift while on the ground any time there is a depress the brakes. This permits the simultaneous application relative headwind. The amount of lift obviously depends on of rudder and brake whenever needed. Some models of the wind speed, but even at slow taxi speeds, the wings and tailwheel airplanes are equipped with heel brakes rather than ailerons are doing their best to aid in liftoff. This phenomenon toe brakes. As in nosewheel airplanes, brakes are used to slow requires care and management, especially during the takeoff and stop the aircraft and to increase turning authority when and landing rolls, and is again unexpected by nosewheel pilots tailwheel steering inputs prove insufficient. Whenever used, making the transition. brakes should be applied smoothly and evenly. Taxiing Instability Because of the relative placement of the main gear and the On most tailwheel-type airplanes, directional control while CG, tailwheel aircraft are inherently unstable on the ground. taxiing is facilitated by the use of a steerable tailwheel, As taxi turns are started, the aircraft begins to pivot on one or which operates along with the rudder. The tailwheel steering the other of the main wheels. From that point, with the CG aft mechanism remains engaged when the tailwheel is operated of that pivot point, the forward momentum of the plane acts through an arc of about 30° each side of center. Beyond that to continue and even tighten the turn without further steering limit, the tailwheel breaks free and becomes full swiveling. In inputs. In consequence, removal of rudder pressure does not full swivel mode, the airplane can be pivoted within its own 13-2

length, if desired. While taxiing, the steerable tailwheel should of light tailwinds, producing a net headwind over the tail. be used for making normal turns and the pilot’s feet kept off This in turn suggests that back stick, not forward, does the the brake pedals to avoid unnecessary wear on the brakes. most to help with directional control. If in doubt, it is best to sample the wind as you taxi and position the elevator where When beginning to taxi, the brakes should be tested it will do the most good. immediately for proper operation. This is done by first applying power to start the airplane moving slowly forward, Weathervaning then retarding the throttle and simultaneously applying pressure smoothly to both brakes. If braking action is Tailwheel airplanes have an exaggerated tendency to unsatisfactory, the engine should be shut down immediately. weathervane, or turn into the wind, when operated on the ground in crosswinds. This tendency is greatest when taxing To turn the airplane on the ground, the pilot should apply with a direct crosswind, a factor that makes maintaining rudder in the desired direction of turn and use whatever power directional control more difficult, sometimes requiring use of or brake necessary to control the taxi speed. At very low taxi the brakes when tailwheel steering alone proves inadequate speeds, directional response is sluggish as surface friction to counteract the weathervane effect. acting on the tailwheel inhibits inputs trough the steering springs. At normal taxi speeds, rudder inputs alone should Visibility be sufficient to start and stop most turns. During taxi, the AOA built in to the structure gives control placement added In the normal nose-high attitude, the engine cowling may be importance when compared to nosewheel models. high enough to restrict the pilot’s vision of the area directly ahead of the airplane while on the ground. Consequently, When taxiing in a quartering headwind, the upwind wing can objects directly ahead are difficult, if not impossible, to see. easily be lifted by gusting or strong winds unless ailerons In aircraft that are completely blind ahead, all taxi movements are positioned to “kill” lift on that side (stick held into the should be started with a small turn to ensure no other plane wind). At the same time, elevator should be held full back or ground vehicle has positioned itself directly under the to add downward pressure to the tailwheel assembly and nose while the pilot’s attention was distracted with getting improve tailwheel steering response. This is standard control ready to takeoff. In taxiing such an airplane, the pilot should positioning for both nosewheel and tailwheel airplanes, so alternately turn the nose from one side to the other (zigzag) the difference lies only in the added tailwheel vulnerability or make a series of short S-turns. This should be done slowly, created by the fuselage pitch attitude. smoothly, positively, and cautiously. When taxiing with a quartering tailwind, this fuselage Directional Control angle reduces the tendency of the wind to lift either wing. Nevertheless, the basic vulnerability to surface winds After absorbing all the information presented to this point, common to all tailwheel airplanes makes it essential to be the transitioning pilot may conclude that the best approach aware of wind direction at all times, so holding the stick away to maintaining directional control is to limit rudder inputs from the cross wind is good practice (left aileron in a right from fear of overcontrolling. Although intuitive, this is quartering tailwind). an incorrect assumption: the disadvantages built in to the tailwheel design sometimes require vigorous rudder inputs Elevator positioning in tailwinds is a bit more complex. to maintain or retain directional control. The best approach is Standard teaching tends to recommend full forward stick in to understand the fact that tailwheel aircraft are not damaged any degree of tailwind, arguing that a tailwind striking the from the use of too much rudder, but rather from rudder elevator when it is deflected full down increases downward inputs held for too long. pressure on the tailwheel assembly and increases directional control. Equally important, if the elevator were to remain Normal Takeoff Roll deflected up, a strong tailwind can get under the control surface and lift the tail with unfortunate consequences for Wing flaps should be lowered prior to takeoff if recommended the propeller and engine. by the manufacturer. After taxiing onto the runway, the airplane should be aligned with the intended takeoff direction, While stick-forward positioning is essential in strong and the tailwheel positioned straight or centered. In airplanes tailwinds, it is not likely to be an appropriate response when equipped with a locking device, the tailwheel should be winds are light. The propeller wash in even lightly-powered locked in the centered position. After releasing the brakes, airplanes is usually strong enough to overcome the effects the throttle should be smoothly and continuously advanced to takeoff power. At all times on the takeoff roll, care must be taken to avoid applying brake pressure. 13-3

After a brief period of acceleration, positive forward elevator airplane encounters a sudden lull in strong, gusty wind or should be applied to smoothly lift the tail. The goal is to other turbulent air currents. In this case, the pilot should achieve a pitch attitude that improves forward visibility hold the airplane on the ground longer to attain more speed, and produces a smooth transition to climbing flight as the then make a smooth, positive rotation to leave the ground. aircraft continues to accelerate. If the attitude chosen is excessively steep, weight transfers rapidly to the wings, Crosswind Takeoff making crosswind control more difficult. If the attitude is too flat, crosswind control is also diminished, a counter- It is important to establish and maintain proper crosswind intuitive result that is discussed in the Crosswind section of corrections prior to lift-off; that is, application of aileron this chapter. deflection into the wind to keep the upwind wing from rising and rudder deflection as needed to prevent weathervaning. It is important to note that nose-down pitch movement Takeoffs made into strong crosswinds are the reason for produces left yaw, the result of gyroscopic precession maintaining a positive AOA (tail-low attitude) while created by the propeller. The amount of force created by this accelerating on the runway. Because the wings are making precession is directly related to the rate the propeller axis is lift during the takeoff roll, a strong upwind aileron deflection tilted when the tail is raised, so it is best to avoid an abrupt can bank the airplane into the wind and provide positive pitch change. Whether smooth or abrupt, the need to react crosswind correction before the aircraft lifts from the runway. to this yaw with rudder inputs emphasizes the increased The remainder of the takeoff roll is then made on the upwind directional demands common to tailwheel airplanes, a main wheel. As the aircraft leaves the runway, the wings can demand likely to be unanticipated by pilots transitioning be leveled as appropriate drift correction (crab) is established. from nosewheel models. Short-Field Takeoff As speed is gained on the runway, the added authority of the elevator naturally continues to pitch the nose forward. With the exception of flap settings and initial climb speed as During this stage, the pilot should concentrate on maintaining recommended by the manufacturer, there is little difference a constant-pitch attitude by gradually reducing elevator between the techniques described above for normal takeoffs. deflection. At the same time, directional control must be After liftoff, the pitch attitude should be adjusted as required maintained with smooth, prompt, positive rudder corrections. for obstacle clearance. All this activity emphasizes the point that tailwheel planes start to “fly” long before leaving the runway surface. Soft-Field Takeoff Liftoff Wing flaps may be lowered prior to starting the takeoff (if recommended by the manufacturer) to provide additional lift When the appropriate pitch attitude is maintained throughout and transfer the airplane’s weight from the wheels to the wings the takeoff roll, liftoff occurs when the AOA and airspeed as early as possible. The airplane should be taxied onto the combine to produce the necessary lift without any additional takeoff surface without stopping on a soft surface. Stopping “rotation” input. The ideal takeoff attitude requires only on a soft surface, such as mud or snow, might bog the airplane minimum pitch adjustments shortly after the airplane lifts down. The airplane should be kept in continuous motion with off to attain the desired climb speed. sufficient power while lining up for the takeoff roll. All modern tailwheel aircraft can be lifted off in the three- As the airplane is aligned with the proposed takeoff path, point attitude. That is, the AOA with all three wheels on the takeoff power is applied smoothly and as rapidly as the ground does not exceed the critical AOA, and the wings will powerplant will accept without faltering. The tail should be not be stalled. While instructive, this technique results in an kept very low to maintain the inherent positive AOA and to unusually high pitch attitude and an AOA excessively close avoid any tendency of the airplane to nose over as a result to stall, both inadvisable circumstances when flying only of soft spots, tall grass, or deep snow. inches from the ground. When the airplane is held at a nose-high attitude throughout As the airplane leaves the ground, the pilot must continue the takeoff run, the wings progressively relieve the wheels of to maintain straight flight and hold the proper pitch attitude. more and more of the airplane’s weight, thereby minimizing During takeoffs in strong, gusty winds, it is advisable to the drag caused by surface irregularities or adhesion. Once add an extra margin of speed before the airplane is allowed airborne, the airplane should be allowed to accelerate to climb to leave the ground. A takeoff at the normal takeoff speed speed in ground effect. may result in a lack of positive control, or a stall, when the 13-4

Landing the airplane is allowed to touch down earlier in the process in a lower pitch attitude, so that the main gear touch while The difference between nosewheel and tailwheel airplanes the tail remains off the runway. becomes apparent when discussing the touchdown and the period of deceleration to taxi speed. In the nosewheel design, Three-Point Landing touchdown is followed quite naturally by a reduction in pitch As with all landings, success begins with an orderly arrival: attitude to bring the nosewheel tire into contact with the airspeed, alignment, and configuration well in hand crossing runway. This pitch change reduces AOA, removes almost the threshold. Round out (level-off) should be made with the all wing lift, and rapidly transfers aircraft weight to the tires. main wheels about one foot off the surface. From that point forward, the technique is essentially the same that is used In tailwheel designs, this reduction of AOA and weight in nosewheels: a gentle increase in AOA to maintain flight transfer are not practical and, as noted in the section on while slowing. In a tailwheel aircraft, however, the goal is Takeoffs, it is rare to encounter tailwheel planes designed to attain a much steeper fuselage angle than that commonly so that the wings are beyond critical AOA in the three-point used in nosewheel models; one that touches the tailwheels attitude. In consequence, the airplane continues to “fly” in at the same time as the mainwheels. the three-point attitude after touchdown, requiring careful attention to heading, roll, and pitch for an extended period. With the tailwheel on the surface, a further increase in pitch attitude is impossible, so the plane remains on the runway, Touchdown albeit tenuously. With deceleration, weight shifts increasingly from wings to wheels, with the final result that the plane Tailwheel airplanes are less forgiving of crosswind landing once again becomes a ground vehicle after shedding most errors than nosewheel models. It is important that touchdown of its speed. occurs with the airplane’s longitudinal axis parallel to the direction the airplane is moving along the runway. There are two potential errors in attempting a three-point [Figure 13-2] Failure to accomplish this imposes Side loads landing. In the first, the mainwheels are allowed to make on the landing gear which leads to directional instability. runway contact a little early with the tail still in the air. To avoid side stresses and directional problems, the pilot With the CG aft of the mainwheels, the tail naturally drops should not allow the airplane to touch down while in a crab when the mainwheels touch, AOA increases, and the plane or while drifting. becomes airborne again. This “skip” is easily managed by re-flaring and again trying to hold the plane off until reaching There are two significantly different techniques used to the three-point attitude. manage tailwheel aircraft touchdowns: three-point and wheel landings. In the first, the airplane is held off the surface of In the second error, the plane is held off the ground a bit too the runway until the attitude needed to remain aloft matches long so that the in-flight pitch attitude is steeper than the the geometry of the landing gear. When touchdown occurs three-point attitude. When touchdown is made in this attitude, at this point, the main gear and the tailwheel make contact at the same time. In the second technique (wheel landings), Normal glide Main gear and tailwheel Hold elevator Start roundout touch down simultaneously full up to landing altitude Figure 13-2. Tailwheel touchdown. 13-5

the tail makes contact first. Provided this happens from no Once the mainwheels are on the surface, the tail should be more than a foot off the surface, the result is undramatic: permitted to drop on its own accord until it too makes ground the tail touches, the plane pitches forward slightly onto the contact. At this point, the elevator should be brought to the mainwheels, and rollout proceeds normally. full aft position and deceleration should be allowed to proceed as in a three-point landing. In every case, once the tailwheel makes contact, the elevator control should be eased fully back to press the tailwheel on NOTE: The only difference between three-point and wheel the runway. Without this elevator input, the AOA of the landings is the timing of the touchdown (early and later). horizontal stabilizer develops enough lift to lighten pressure There is no difference between the approach angles and on the tailwheel and render it useless as a directional control airspeeds in the two techniques. with possibly unwelcome consequences. This after-landing elevator input is quite foreign to nosewheel pilots and must Crosswinds be stressed during transition training. As noted, it is highly desirable to eliminate crab and drift at touchdown. By far the best approach to crosswind NOTE: Before the tailwheel is on the ground, application of management is a side-slip or wing-low touchdown. Landing full back elevator during the flare lowers the tail, increases the in this attitude, only one mainwheel makes initial contact, AOA, and quite naturally puts the plane in climbing flight. either in concert with the tailwheel in three-point landings or by itself in wheel landings. Wheel Landing In some wind conditions, the need to retain control authority After-Landing Roll may make it desirable to make contact with the runway at a higher airspeed than that associated with the three-point The landing process must never be considered complete attitude. This necessitates landing in a flatter pitch attitude on until the airplane decelerates to the normal taxi speed during the mainwheels only, with the tailwheel still off the surface. the landing roll or has been brought to a complete stop [Figure 13-3] As noted, if the tail is off the ground, it tends when clear of the landing area. The pilot must be alert for to drop and put the plane airborne, so a soft touchdown and a directional control difficulties immediately upon and after slight relaxation of back elevator just after the wheels touch touchdown, and the elevator control should be held back as are key ingredients to a successful wheel landing. far as possible and as firmly as possible until the airplane stops. This provides more positive control with tailwheel If the touchdown is made at too high a rate of descent, the tail is steering, tends to shorten the after-landing roll, and prevents forced down by its own weight, resulting in a sudden increase bouncing and skipping. in lift. If the pilot now pushes forward in an attempt to again make contact with the surface, a potentially dangerous pilot- Any difference between the direction the airplane is traveling induced oscillation may develop. It is far better to respond to and the direction it is headed (drift or crab) produces a moment a bounced wheel landing attempt by initiating a go-around about the pivot point of the wheels, and the airplane tends to or converting to a three-point landing if conditions permit. swerve. Loss of directional control may lead to an aggravated, uncontrolled, tight turn on the ground, or a ground loop. The Normal glide CROSS WIND Start roundout Hold the airplane in Immediately but As the airplane’s speed to landing altitude level flight attitude smoothly retard the throttle, continues to decrease, until the main wheels and hold sufficient forward the tail may be allowed to touch. The tailwheel elevator pressure to hold the main slowly touch the ground. should be held clear of wheels on the ground. the runway. Figure 13-3. Wheel landing. 13-6

combination of inertia acting on the CG and ground friction of Crosswind After-Landing Roll the main wheels during the ground loop may cause the airplane to tip enough for the outside wingtip to contact the ground and Particularly during the after-landing roll, special attention may even impose a sideward force that could collapse one must be given to maintaining directional control by the use landing gear leg. [Figure 13-4] In general, this combination of rudder and tailwheel steering while keeping the upwind of events is eliminated by landing straight and avoiding turns wing from rising by the use of aileron. Characteristically, an at higher than normal running speed. airplane has a greater profile or side area behind the main landing gear than forward of it. With the main wheels acting To use the brakes, the pilot should slide the toes or feet up as a pivot point and the greater surface area exposed to the from the rudder pedals to the brake pedals (or apply heel crosswind behind that pivot point, the airplane tends to turn or pressure in airplanes equipped with heel brakes). If rudder weathervane into the wind. [Figure 13-5] This weathervaning pressure is being held at the time braking action is needed, tendency is more prevalent in the tailwheel-type because the that pressure should not be released as the feet or toes are airplane’s surface area behind the main landing gear is greater being slid up to the brake pedals because control may be than in nosewheel-type airplanes. lost before brakes can be applied. During the ground roll, the airplane’s direction of movement may be changed by Pilots should be familiar with the crosswind component of carefully applying pressure on one brake or uneven pressures each airplane they fly and avoid operations in wind conditions on each brake in the desired direction. Caution must be that exceed the capability of the airplane, as well as their exercised when applying brakes to avoid overcontrolling. own limitations. While the airplane is decelerating during the after-landing roll, more aileron must be applied to keep If a wing starts to rise, aileron control should be applied the upwind wing from rising. Since the airplane is slowing toward that wing to lower it. The amount required depends on down, there is less airflow around the ailerons and they speed because as the forward speed of the airplane decreases, become less effective. At the same time, the relative wind is the ailerons become less effective. becoming more of a crosswind and exerting a greater lifting force on the upwind wing. Consequently, when the airplane If available runway permits, the speed of the airplane should is coming to a stop, the aileron control must be held fully be allowed to dissipate in a normal manner by the friction toward the wind. and drag of the wheels on the ground. Brakes may be used if needed to help slow the airplane. After the airplane has been Short-Field Landing slowed sufficiently and has been turned onto a taxiway or clear of the landing area, it should be brought to a complete Upon touchdown, the airplane should be firmly held in a stop. Only after this is done should the pilot retract the flaps three-point attitude. This provides aerodynamic braking and perform other checklist items. by the wings. Immediately upon touchdown and closing the throttle, the brakes should be applied evenly and firmly Motion to minimize the after-landing roll. The airplane should be stopped within the shortest possible distance consistent with safety. Point of wheel pivoting CG Profile behind pivot point Figure 13-5. Weathervaning tendency. Figure 13-4. Effect of CG on directional control. 13-7

Soft-Field Landing To counteract the possibility of an uncontrolled turn, the pilot should counter any swerve with firm rudder input. In stronger The tailwheel should touchdown simultaneously with or swerves, differential braking is essential as tailwheel steering just before the main wheels and should then be held down proves inadequate. It is important to note, however, that as by maintaining firm back-elevator pressure throughout the corrections begin to become apparent, rudder and braking landing roll. This minimizes any tendency for the airplane inputs need to be removed promptly to avoid starting yet to nose over and provides aerodynamic braking. The use of another departure in the opposite direction. brakes on a soft field is not needed because the soft or rough surface itself provides sufficient reduction in the airplane’s Chapter Summary forward speed. Often, it is found that upon landing on a very soft field, the pilot needs to increase power to keep the This chapter focuses on the operational differences between airplane moving and from becoming stuck in the soft surface. tailwheel and nosewheel airplanes that occur during ground operations, takeoffs, and landings. The chapter covers Ground Loop specific topics, such as landing gear, taxiing, visibility, liftoff, and landing. Comparisons are given as to how each A ground loop is an uncontrolled turn during ground react during the takeoff and landing, as well as situations operations that may occur during taxi, takeoff, or during that should be avoided. Pilots who use proper rudder control the after-landing roll. Ground loops start with a swerve that techniques should be able to transition to tailwheel airplanes is allowed to continue for too long. The swerve may be without too much difficulty. the result of side-load on landing, a taxi turn started with too much groundspeed, overcorrection, or even an uneven ground surface or a soft spot that retards one main wheel of the airplane. Due to the inbuilt instability of the tailwheel design, the forces that lead to a ground loop accumulate as the angle between the fuselage and inertia, acting from the CG, increase. If allowed to develop, these forces may become great enough to tip the airplane to the outside of the turn until one wing strikes the ground. 13-8

Chapter 14 Transition to Turbopropeller- Powered Airplanes Introduction The turbopropeller-powered airplane flies and handles just like any other airplane of comparable size and weight. The aerodynamics are the same. The major differences between flying a turboprop and other non-turbine-powered airplanes are found in the handling of the airplane’s powerplant and its associated systems. The powerplant is different and requires operating procedures that are unique to gas turbine engines. But so, too, are other systems, such as electrical, hydraulics, environmental, flight control, rain and ice protection, and avionics. The turbopropeller-powered airplane also has the advantage of being equipped with a constant speed, full feathering and reversing propeller—something normally not found on piston-powered airplanes. 14-1

Gas Turbine Engine the high velocity excess exhaust exits the tail pipe or exhaust section. (The exhaust section of a turbojet engine may also Both piston (reciprocating) engines and gas turbine engines incorporate a system of moving doors to redirect airflow are internal combustion engines. They have a similar for the purpose of slowing an airplane down after landing cycle of operation that consists of induction, compression, or back-powering it away from a gate. They are referred to combustion, expansion, and exhaust. In a piston engine, as thrust reversers). Once the turbine section is powered by each of these events is a separate distinct occurrence in each gases from the burner section, the starter is disengaged, and cylinder. Also in a piston engine, an ignition event must occur the igniters are turned off. Combustion continues until the during each cycle in each cylinder. Unlike reciprocating engine is shut down by turning off the fuel supply. engines, in gas turbine engines these phases of power occur simultaneously and continuously instead of successively NOTE: Because compression produces heat, some pneumatic one cycle at a time. Additionally, ignition occurs during the aircraft systems tap into the source of hot (480 °F) compressed starting cycle and is continuous thereafter. The basic gas air from the engine compressor (bleed air) and use it for turbine engine contains four sections: intake, compression, engine anti-ice, airfoil anti-ice, aircraft pressurization, and combustion, and exhaust. [Figure 14-1] other ancillary systems after further conditioning its internal pressure and temperature. To start the engine, the compressor section is rotated by an electrical starter on small engines or an air-driven High-pressure exhaust gases can be used to provide jet thrust starter on large engines. As compressor rates per minute as in a turbojet engine. Or, the gases can be directed through (rpm) accelerates, air is brought in through the inlet an additional turbine to drive a propeller through reduction duct, compressed to a high pressure, and delivered to the gearing, as in a turbopropeller (turboprop) engine. combustion section (combustion chambers). Fuel is then injected by a fuel controller through spray nozzles and ignited Turboprop Engines by igniter plugs. (Not all of the compressed air is used to support combustion. Some of the compressed air bypasses The turbojet engine excels the reciprocating engine in the burner section and circulates within the engine to provide top speed and altitude performance. On the other hand, internal cooling, enhanced thrust, and noise abatement. In the turbojet engine has limited takeoff and initial climb turbojet engines, by-pass airflow may be augmented by performance as compared to that of a reciprocating engine. the action of a fan located at the engine’s intake.) The fuel/ In the matter of takeoff and initial climb performance, the air mixture in the combustion chamber is then burned in a reciprocating engine is superior to the turbojet engine. continuous combustion process and produces a very high Turbojet engines are most efficient at high speeds and temperature, typically around 4,000° Fahrenheit (F), which high altitudes, while propellers are most efficient at slow heats the entire air mass to 1,600 – 2,400 °F. The mixture of and medium speeds (less than 400 miles per hour (mph)). hot air and gases expands and is directed to the turbine blades Propellers also improve takeoff and climb performance. forcing the turbine section to rotate, which in turn drives the The development of the turboprop engine was an attempt to compressor by means of a direct shaft, a concentric shaft, or combine in one engine the best characteristics of both the a combination of both. After powering the turbine section, turbojet and propeller-driven reciprocating engine. INTAKE COMPRESSION COMBUSTION EXHAUST Air inlet Compression Combustion chambers Turbine Exhaust Cold section Hot section Figure 14-1. Basic components of a gas turbine engine. 14-2

The turboprop engine offers several advantages over other per horsepower per hour) is increased. Decreased specific types of engines, such as: fuel consumption plus the increased true airspeed at higher altitudes is a definite advantage of a turboprop engine. • Lightweight All turbine engines, turboprop or turbojet, are defined by • Mechanical reliability due to relatively few moving limiting temperatures, rotational speeds, and (in the case parts of turboprops) torque. Depending on the installation, the primary parameter for power setting might be temperature, • Simplicity of operation torque, fuel flow, or rpm (either propeller rpm, gas generator (compressor) rpm, or both). In cold weather conditions, • Minimum vibration torque limits can be exceeded while temperature limits are still within acceptable range. While in hot weather conditions, • High power per unit of weight temperature limits may be exceeded without exceeding torque limits. In any weather, the maximum power setting • Use of propeller for takeoff and landing of a turbine engine is usually obtained with the throttles positioned somewhat aft of the full forward position. The Turboprop engines are most efficient at speeds between 250 transitioning pilot must understand the importance of and 400 mph and altitudes between 18,000 and 30,000 feet. knowing and observing limits on turbine engines. An over They also perform well at the slow speeds required for takeoff temperature or over torque condition that lasts for more than a and landing and are fuel efficient. The minimum specific fuel few seconds can literally destroy internal engine components. consumption of the turboprop engine is normally available in the altitude range of 25,000 feet up to the tropopause. Turboprop Engine Types The power output of a piston engine is measured in Fixed Shaft horsepower and is determined primarily by rpm and manifold One type of turboprop engine is the fixed shaft constant speed pressure. The power of a turboprop engine, however, is type, such as the Garrett TPE331. [Figure 14-2] In this type measured in shaft horsepower (shp). Shaft horsepower is engine, ambient air is directed to the compressor section determined by the rpm and the torque (twisting moment) through the engine inlet. An acceleration/diffusion process applied to the propeller shaft. Since turboprop engines in the two stage compressor increases air pressure and directs are gas turbine engines, some jet thrust is produced by it rearward to a combustor. The combustor is made up of a exhaust leaving the engine. This thrust is added to the shaft combustion chamber, a transition liner, and a turbine plenum. horsepower to determine the total engine power or equivalent Atomized fuel is added to the air in the combustion chamber. shaft horsepower (eshp). Jet thrust usually accounts for less Air also surrounds the combustion chamber to provide for than 10 percent of the total engine power. cooling and insulation of the combustor. Although the turboprop engine is more complicated and The gas mixture is initially ignited by high-energy igniter heavier than a turbojet engine of equivalent size and power, plugs, and the expanding combustion gases flow to the it delivers more thrust at low subsonic airspeeds. However, turbine. The energy of the hot, high-velocity gases is the advantages decrease as flight speed increases. In normal converted to torque on the main shaft by the turbine rotors. cruising speed ranges, the propulsive efficiency (output The reduction gear converts the high rpm—low torque of the divided by input) of a turboprop decreases as speed increases. main shaft to low rpm—high torque to drive the accessories and the propeller. The spent gases leaving the turbine are The propeller of a typical turboprop engine is responsible directed to the atmosphere by the exhaust pipe. for roughly 90 percent of the total thrust under sea level conditions on a standard day. The excellent performance of a Only about 10 percent of the air that passes through the turboprop during takeoff and climb is the result of the ability engine is actually used in the combustion process. Up to of the propeller to accelerate a large mass of air while the approximately 20 percent of the compressed air may be bled airplane is moving at a relatively low ground and flight speed. off for the purpose of heating, cooling, cabin pressurization, “Turboprop,” however, should not be confused with “turbo and pneumatic systems. Over half the engine power is supercharged” or similar terminology. All turbine engines devoted to driving the compressor, and it is the compressor have a similarity to normally aspirated (non-supercharged) that can potentially produce very high drag in the case of a reciprocating engines in that maximum available power failed, windmilling engine. decreases almost as a direct function of increased altitude. Although power decreases as the airplane climbs to higher altitudes, engine efficiency in terms of specific fuel consumption (expressed as pounds of fuel consumed 14-3

Planetary production gears Reverse-flow annular combustion chamber Three stage axial turbine Fuel nozzle Igniter Exhaust outlet Air inlet Second-stage centrifugal compressor First-stage centrifugal compressor Figure 14-2. Fixed shaft turboprop engine. In the fixed shaft constant-speed engine, the engine rpm forward thrust. The power lever is also used to provide may be varied within a narrow range of 96 percent to 100 reverse thrust. The condition lever sets the desired engine rpm percent. During ground operation, the rpm may be reduced within a narrow range between that appropriate for ground to 70 percent. In flight, the engine operates at a constant operations and flight. speed that is maintained by the governing section of the Powerplant instrumentation in a fixed shaft turboprop propeller. Power changes are made by increasing fuel flow engine typically consists of the following basic indicators. and propeller blade angle rather than engine speed. An [Figure 14-4] increase in fuel flow causes an increase in temperature and a corresponding increase in energy available to the turbine. • Torque or horsepower The turbine absorbs more energy and transmits it to the • Interturbine temperature (ITT) propeller in the form of torque. The increased torque forces • Fuel flow the propeller blade angle to be increased to maintain the • RPM constant speed. Turbine temperature is a very important factor to be considered in power production. It is directly GA Condition levers related to fuel flow and thus to the power produced. It must be limited because of strength and durability of the material in the combustion and turbine section. The control system schedules fuel flow to produce specific temperatures and to limit those temperatures so that the temperature tolerances of the combustion and turbine sections are not exceeded. The engine is designed to operate for its entire life at 100 percent. All of its components, such as compressors and turbines, are most efficient when operated at or near the rpm design point. Powerplant (engine and propeller) control is achieved by Power levers means of a power lever and a condition lever for each engine. [Figure 14-3] There is no mixture control and/or rpm lever as found on piston-engine airplanes. On the fixed shaft constant-speed turboprop engine, the Figure 14-3. Powerplant controls—fixed shaft turboprop engine. power lever is advanced or retarded to increase or decrease 14-4

NAV1 108.00 113.00 NAV1 108.00 113.00 WPT _ _ _ _ _ _ DIS _ _ ._ NM DTK _ _ _° TRK 360° 134.000 118.000 COM1 NAV2 108.00 110.60 NAV2 108.00 110.60 123.800 118.000 COM2 23.0 23.0 130 44030000 2 120 4200 2300 2300 1110 270° 4100 1 13.7 13.7 100 46 46 VOR 1 60 1 200 200 9 2 44000000 1652 1652 90 20 80 1 1 70 3900 338 338 TAS 100KT 3800 5 5 4300 3600 3500 3400 3300 XPDR 553732I00DNT LCL23:00:34 ALERTS 3100 Figure 14-4. Powerplant instrumentation—fixed shaft turboprop engine. Torque developed by the turbine section is measured by a of the propeller blades automatically toward their feathered torque sensor. The torque is then reflected on the instrument position should the engine suddenly lose power while in panel horsepower gauge calibrated in horsepower times 100. flight. The NTS system is an emergency backup system in ITT is a measurement of the combustion gas temperature the event of sudden engine failure. It is not a substitution between the first and second stages of the turbine section. The for the feathering device controlled by the condition lever. gauge is calibrated in degrees Celsius (°C). Propeller rpm is reflected on a tachometer as a percentage of maximum rpm. Split Shaft/ Free Turbine Engine Normally, a vernier indicator on the gauge dial indicates In a free power-turbine engine, such as the Pratt & Whitney rpm in 1 percent graduations as well. The fuel flow indicator PT-6 engine, the propeller is driven by a separate turbine indicates fuel flow rate in pounds per hour. through reduction gearing. The propeller is not on the same shaft as the basic engine turbine and compressor. Propeller feathering in a fixed shaft constant-speed turboprop [Figure 14-5] Unlike the fixed shaft engine, in the split engine is normally accomplished with the condition lever. shaft engine the propeller can be feathered in flight or on the An engine failure in this type engine, however, results in a ground with the basic engine still running. The free power- serious drag condition due to the large power requirements of turbine design allows the pilot to select a desired propeller the compressor being absorbed by the propeller. This could governing rpm, regardless of basic engine rpm. create a serious airplane control problem in twin-engine airplanes unless the failure is recognized immediately and A typical free power-turbine engine has two independent the affected propeller feathered. For this reason, the fixed counter-rotating turbines. One turbine drives the compressor, shaft turboprop engine is equipped with negative torque while the other drives the propeller through a reduction sensing (NTS). gearbox. The compressor in the basic engine consists of three axial flow compressor stages combined with a single NTS is a condition wherein propeller torque drives the engine, centrifugal compressor stage. The axial and centrifugal stages and the propeller is automatically driven to high pitch to are assembled on the same shaft and operate as a single unit. reduce drag. The function of the negative torque sensing system is to limit the torque the engine can extract from the Inlet air enters the engine via a circular plenum near the propeller during windmilling and thereby prevent large drag rear of the engine and flows forward through the successive forces on the airplane. The NTS system causes a movement compressor stages. The flow is directed outward by the 14-5

Exhaust outlet Three stage axial flow compressor Accessory gearbox Reduction gearbox Fuel nozzle Igniter Air inlet Propeller drive shaft Fuel nozzle Igniter Centrifugal compressor Free (power) turbine Compressor turbine (gas producer) Figure 14-5. Split shaft/free turbine engine. centrifugal compressor stage through radial diffusers before lever is located at the far right of the power quadrant. But entering the combustion chamber, where the flow direction the condition lever on a turboprop engine is really just an is actually reversed. The gases produced by combustion on/off valve for delivering fuel. There are HIGH IDLE and are once again reversed to expand forward through each LOW IDLE positions for ground operations, but condition turbine stage. After leaving the turbines, the gases are levers have no metering function. Leaning is not required in collected in a peripheral exhaust scroll and are discharged turbine engines; this function is performed automatically by to the atmosphere through two exhaust ports near the front a dedicated fuel control unit. of the engine. Engine instruments in a split shaft/free turbine engine A pneumatic fuel control system schedules fuel flow to typically consist of the following basic indicators. maintain the power set by the gas generator power lever. [Figure 14-7] Except in the beta range, propeller speed within the governing range remains constant at any selected propeller control lever • ITT indicator position through the action of a propeller governor. • Torquemeter The accessory drive at the aft end of the engine provides power to drive fuel pumps, fuel control, oil pumps, a starter/ • Propeller tachometer generator, and a tachometer transmitter. At this point, the speed of the drive (N1) is the true speed of the compressor • N1 (gas generator) tachometer side of the engine, approximately 37,500 rpm. • Fuel flow indicator Powerplant (engine and propeller) operation is achieved by three sets of controls for each engine: the power lever, • Oil temperature/pressure indicator propeller lever, and condition lever. [Figure 14-6] The power lever serves to control engine power in the range The ITT indicator gives an instantaneous reading of engine from idle through takeoff power. Forward or aft motion of gas temperature between the compressor turbine and the the power lever increases or decreases gas generator rpm power turbines. The torquemeter responds to power lever (N1) and thereby increases or decreases engine power. The movement and gives an indication in foot-pounds (ft/lb) propeller lever is operated conventionally and controls the of the torque being applied to the propeller. Because in the constant-speed propellers through the primary governor. The free turbine engine the propeller is not attached physically propeller rpm range is normally from 1,500 to 1,900. The to the shaft of the gas turbine engine, two tachometers are condition lever controls the flow of fuel to the engine. Like justified—one for the propeller and one for the gas generator. the mixture lever in a piston-powered airplane, the condition The propeller tachometer is read directly in revolutions per minute. The N1 or gas generator is read in percent of rpm. In the Pratt & Whitney PT-6 engine, it is based on a figure of 37,000 rpm at 100 percent. Maximum continuous gas generator is limited to 38,100 rpm or 101.5 percent N1. 14-6