Multi-Engine Add-On Study Guide

Redundancy and performance — but only conditionally. The AFH is blunt about it: the performance and system redundancy of a multiengine airplane only increase safety if the pilot is trained and proficient (AFH ch. 13).

The airplane doesn't save you. Training and proficiency do. That is the entire premise of the class rating.

Because climb comes from excess power, not total power.

• Loss of one engine is a loss of 50 percent of power
• That reduces climb performance by 80 to 90 percent (AFH ch. 13)

Level flight consumes most of what the engines produce. What's left over is climb — and one engine's worth of thrust barely covers the level-flight requirement.

Performance and control.

• Performance — climb capability may be marginal or simply nonexistent
• Control — asymmetrical thrust yaws and rolls the airplane toward the dead engine

A single-engine airplane only hands you a performance problem. A twin hands you both at once, and the AFH says attention to both is crucial to safe OEI flight (AFH ch. 13).

• Small multiengine airplane — a reciprocating or turbopropeller-powered airplane with a maximum certificated takeoff weight of 12,500 lb or less
• Light twin — not formally defined in the regulations; the AFH uses it for a small multiengine airplane of 6,000 lb or less maximum certificated takeoff weight (AFH ch. 13)

Generally, no — and this is the single most important thing to understand about the airplane you're about to fly.

Under the historical part 23 requirements, for an airplane of 6,000 lb or less maximum weight with VSO of 61 knots or less, the single-engine rate of climb at 5,000 ft MSL must simply be determined. The rate of climb could be a negative number. There is no requirement for a positive single-engine rate of climb at 5,000 feet or any other altitude (AFH ch. 13).

• Red radial line — VMC, the minimum control speed. This is the control problem.
• Blue radial line — VYSE, best rate of climb with one engine inoperative. This is the performance problem.

The AFH's chapter summary frames the whole discipline around exactly these two markings (AFH ch. 13). Your own numbers come from your AFM/POH — never assume a number you learned in another twin.

• Loss of directional control
• Loss of performance
• Loss of flying speed

All three have equal potential to be lethal. Loss of flying speed is not a factor, however, when the airplane is operated with due regard for directional control and performance (AFH ch. 13).

Analysis of engine failures on takeoff reveals:

• A very high success rate of off-airport engine-inoperative landings when the airplane is landed under control
• A very high fatality rate in stall-spin accidents when the pilot attempts flight beyond the performance capability of the airplane (AFH ch. 13)

The airplane is rarely the variable. The decision is.

Attempting to fly when it is not within the performance capability of the airplane to do so. The AFH's verdict: an accident is inevitable.

Remaining airborne and bleeding off airspeed in a futile attempt to maintain altitude is almost invariably fatal. Landing under control is paramount (AFH ch. 13).

No multiengine airplane is approved for spins, and their spin recovery characteristics are generally very poor. Very few twins have ever been spin-tested — none are required to be (AFH ch. 13).

Practice spin avoidance and stay alert to the setups that produce one: VMC demonstrations, stall practice, slow flight, or any condition of high asymmetrical thrust at low speed and high AOA.

The airplane manufacturer. The AFM/POH guidance and procedures take precedence over any general recommendation in the AFH or in any training text — including this one (AFH ch. 13).

Every speed in this guide is a concept. Every number is in your book.

Because the OEI flight regime has no analog in single-engine flying. Mastery of OEI flight is only one aspect of safe multiengine flying, but it is the aspect that distinguishes the class — and the modern, well-equipped multiengine airplane can be remarkably capable when the pilot is proficient (AFH ch. 13).

• Rate of climb — altitude gained per unit of time (fpm)
• Climb gradient — altitude gained per 100 feet of horizontal travel, expressed as a percentage. A gain of 1.5 ft per 100 ft (15 ft per 1,000, 150 ft per 10,000) is a 1.5 percent gradient (AFH ch. 13)

Gradient matters because, unlike rate of climb, climb gradient is affected by wind — improved by a headwind component, reduced by a tailwind (AFH ch. 13). Obstacles care about gradient, not rate.

No. The performance characteristics of an airplane depend upon the rules in effect during type certification and do not depend on the production year after certification (AFH ch. 13).

Don't confuse the date of type certification with the airplane's model year — the type certification basis of many multiengine airplanes dates back to the Civil Aviation Regulations (CAR) 3 (AFH ch. 13).

The current amendment to 14 CFR part 23 (81 FR 96689) went into effect December 30, 2016, covering normal category airplanes with 19 or fewer passenger seats and 19,000 lb or less maximum certificated takeoff weight (23.2005(a)).

Airplanes are sorted into certification levels 1 through 4 by passenger seating (23.2005(b)) and into two performance levels by speed (23.2005(c)).

Example: a level 2 low-speed airplane that does not meet single-engine crashworthiness requirements needs a climb gradient of at least 1.5 percent at 5,000 ft pressure altitude in the cruise configuration (23.2120(b)(1)).

Two categories (AFH ch. 13):

More than 6,000 lb and/or VSO more than 61 knots — single-engine rate of climb at 5,000 ft MSL must be at least 0.027 × VSO² fpm. For airplanes type certificated February 4, 1991 or later, expressed instead as a 1.5 percent climb gradient. (The gradient is not a direct equivalent of the 0.027 VSO² formula.)

6,000 lb or less and VSO 61 knots or less — the rate of climb must simply be determined, and may be negative. For light twins type certificated February 4, 1991 or later, the gradient (positive or negative) is simply determined.

Very. The AFH notes that the modern well-maintained reciprocating engine is remarkably reliable (AFH ch. 13).

That's worth holding alongside everything else in this guide. Training risk is real: stall-spin accidents in training for emergencies rival the number of stall-spin accidents from actual emergencies (AFH ch. 13). The discipline you're learning is meant to make both columns smaller.

VMC is the calibrated airspeed at which, following the sudden critical loss of thrust, it is possible to maintain control of the airplane. It's marked with a red radial line on the airspeed indicator (14 CFR 23.2135(c); AFH ch. 13).

The previous definition, in 23.149, still applies to airplanes certificated under that rule: the calibrated airspeed at which, when the critical engine is suddenly made inoperative, it is possible to maintain control of the airplane with that engine still inoperative, and thereafter maintain straight flight at the same speed with a bank angle of not more than 5 degrees.

No. There is no requirement under either determination that the airplane be capable of climbing at this airspeed — VMC only addresses directional control (AFH ch. 13).

This is the trap. Red line is a controllability floor, not a performance promise. Blue line (VYSE) is where performance lives.

No — VMC is a fixed airspeed only for the very specific set of circumstances under which it was determined during aircraft certification. This is the core of the subject: in reality VMC varies with a variety of factors, and the VMC you encounter in practice, in demonstration, or in an actual OEI situation could be less or even greater than the published value, depending on conditions and pilot technique (AFH ch. 13).

Historically, dynamic VMC was determined with (AFH ch. 13, citing 23.149):

• Maximum available takeoff power initially on each engine — 23.149(b)(1)
• Propeller controls in the recommended takeoff position — 23.149(b)(5)
• Most unfavorable weight and CG — 23.149(b)
• Landing gear retracted — 23.149(b)(4)
• Flaps in the takeoff position — 23.149(b)(3)
• Airplane trimmed for takeoff — 23.149(b)(2)
• Airborne, ground effect negligible — 23.149(b)
• Maximum 5 degrees of bank — 23.149(a)

Also: critical engine inoperative, and the value published as a sea level calibrated airspeed.

VMC increases as power is increased on the operating engine.

Normally aspirated: VMC is highest at takeoff power and sea level, and decreases with altitude as available power falls off.

Turbocharged: takeoff power, and therefore VMC, remains constant with altitude up to the engine's critical altitude (the altitude at which the engine can no longer maintain 100 percent power). Above critical altitude, VMC decreases as it would with a normally aspirated engine (AFH ch. 13).

VMC increases with increased drag on the inoperative engine — it's therefore highest when the critical engine's propeller is windmilling at the low pitch, high rpm blade angle.

VMC is normally determined with the critical engine propeller windmilling in the takeoff position — unless the engine is equipped with an autofeather system (AFH ch. 13, 23.149(b)(5)).

Practical consequence: feathering lowers actual VMC as well as reducing drag.

VMC increases as the CG moves aft, since the rudder's moment arm — and its effectiveness — is reduced; for a typical light twin the aft-most CG limit is the most unfavorable CG position. VMC also increases as weight is reduced (AFH ch. 13).

Historically part 23 called for VMC to be determined at the most unfavorable weight; for twins certificated under CAR 3 or early part 23, the weight at which VMC was determined was not specified (AFH ch. 13).

VMC increases when the landing gear is retracted, since extended gear aids directional stability, which tends to decrease VMC (AFH ch. 13, 23.149(b)(4)).

So the certification condition — gear up — is the conservative one.

Because bank angle moves VMC faster than any other variable — VMC increases as bank decreases. It can increase more than 3 knots per degree of bank lost between 5 degrees and wings level.

Since VMC was determined with up to 5 degrees of bank, loss of directional control may be experienced at speeds almost 20 knots above published VMC when the wings are held level (AFH ch. 13).

Wings level is not neutral. It is the worst case.

The horizontal component of lift generated by the bank balances the side force from the rudder, rather than using sideslip to do so. Sideslip requires more rudder deflection, which in turn increases VMC (AFH ch. 13, 23.149(a)).

The 5-degree allowance exists to prevent claims of an unrealistically low VMC — but the AFH warns that high bank angles may result in unsafe flight from both the large sideslip and the need to increase AOA to maintain the vertical component of lift.

No. The 5-degree bank maximum is a historical limit imposed upon manufacturers in aircraft certification. It does not inherently establish zero sideslip or best single-engine climb performance — zero sideslip, and therefore best single-engine climb, may occur at bank angles less than 5 degrees (AFH ch. 13).

Certification VMC is solely concerned with the minimum speed for directional control under a very specific set of circumstances, not the optimum attitude or configuration for climb.

With normally aspirated engines VMC decreases with altitude, but stalling speed (VS) remains the same.

• Except for a few models, published VMC is almost always higher than VS
• At sea level there is usually a margin of several knots
• The margin decreases with altitude, and at some altitude VMC and VS are the same (AFH ch. 13)

Should a stall occur under asymmetrical power, a spin entry is likely — and the airplane departs in the direction of the idle engine, not in the direction of applied rudder.

On the ground, engine fails below VMC: the takeoff must be rejected — directional control can only be maintained by promptly closing both throttles and using rudder and brakes as required. Airborne below VMC: directional control is not possible with the remaining engine producing takeoff power.

Therefore, on takeoff, the airplane should never be airborne before the airspeed exceeds VMC (AFH ch. 13). Use the manufacturer's VR or VLOF; if none is published, use a minimum of VMC plus 5 knots for VR.

Dynamic: the critical engine is suddenly made inoperative and control is maintained thereafter. In certification, test pilots performed mixture cuts of the critical engine while gradually reducing speed with each attempt. VMC was the minimum speed at which directional control could be maintained within 20 degrees of the original entry heading (AFH ch. 13).

Static (steady-state): simply the ability to maintain straight flight at VMC with a bank angle of not more than 5 degrees.

If the two differ, the higher of the two is published as VMC (AFH ch. 13). The static determination more closely resembles the VMC demonstration task on the practical test.

Because the dynamic technique is used only by highly experienced test pilots during aircraft certification — attempting it outside those circumstances is unsafe (AFH ch. 13).

During those tests the climb angle with both engines operating was high, and pitch had to be lowered quickly after the cut to regain speed. The AFH's warning to transitioning pilots is explicit: attempting to demonstrate VMC with an engine cut from high power, or intentionally failing an engine at speeds less than VSSE, creates a high likelihood for loss of control and an accident.

1. Select an altitude allowing the maneuver at least 3,000 ft AGL
2. Landing gear retracted, flaps in the takeoff position
3. Slow to approximately 10 knots above VSSE or VYSE, whichever is higher, and trim for takeoff — the trim setting then remains unaltered for the rest of the maneuver
4. Select an entry heading; set high rpm on both propeller controls
5. Throttle the left engine to idle as the right engine is advanced to takeoff power
6. Counteract the left yawing and rolling moment primarily with right rudder; establish a bank of up to 5 degrees toward the operating engine as appropriate for the make and model
7. Holding heading, slowly increase pitch to decelerate at 1 knot per second (no faster)
8. Rudder pressure and aileron displacement both increase as control effectiveness decays

(AFH ch. 13)

The trigger is either of two things — the moment you first recognize uncontrollable yaw, or any symptom associated with a stall.

Recovery is simultaneous: retard the throttle of the operating engine to stop the yaw, and lower the pitch attitude to regain speed.

Recover to straight flight on the entry heading at VSSE or VYSE, then increase power on the operating engine and demonstrate controlled flight before restoring symmetrical power (AFH ch. 13).

No — maintaining altitude is not a criterion. This is a demonstration of controllability, not performance — many airplanes lose (or gain) altitude during it. Remaining at or above 3,000 ft AGL throughout is considered effective risk mitigation (AFH ch. 13).

Certification permitted 150 pounds of force under the historical rule (23.149(e)). Most twins will run out of rudder travel long before 150 pounds is required — but the pressure during any VMC demonstration may still seem considerable (AFH ch. 13).

An actual demonstration may not be possible at certain density altitudes, or in airplanes whose VMC is equal to or less than VS. Under those circumstances a demonstration may be safely conducted as a training technique by artificially limiting rudder travel to simulate maximum available rudder, at a speed well above VS — approximately 20 knots (AFH ch. 13).

This rudder-limiting technique avoids the hazard of spinning from a stall under high asymmetrical power while still demonstrating the loss of directional control.

A single-engine stall. A VMC demonstration that degrades into a single-engine stall with high asymmetrical thrust may result in an unrecoverable loss of control and a fatal accident (AFH ch. 13).

Terminate immediately on any stall warning light or horn, airframe or elevator buffet, or sudden loss of control effectiveness — reduce the AOA as the throttle is retarded. Be aware that flight deck noise may mask the sound of the stall warning horn (AFH ch. 13).

Also: avoid performing any VMC demonstration from a high pitch attitude with both engines operating and then reducing power on one.

Any departure from the certification conditions in the unfavorable direction (AFH ch. 13):

• Less bank than 5 degrees toward the operating engine — the big one, more than 3 kt per degree
• Wings level — up to nearly 20 kt above published
• Aft CG — reduced rudder moment arm
• Lighter weight
• Windmilling (unfeathered) propeller on the failed engine
• High power on the operating engine
• Gear retracted

The same factors run in reverse lower it: feathering, gear down, more bank toward the good engine, and altitude with normally aspirated engines.

Turbocharging is the trap in that last one — it doesn't raise VMC, it takes away the decrease. Takeoff power, and therefore VMC, stays constant up to the engine's critical altitude, so at altitude your actual VMC is still the published sea-level value while Vs has climbed to meet it, narrowing the margin you were counting on (AFH ch. 13).

The same list also explains zero-sideslip technique: roughly 2 degrees of bank puts your actual VMC above the published figure — an accepted trade for climb performance, not an oversight (AFH ch. 13).

The engine whose failure has the most adverse effect on directional control (AFH ch. 13).

That's the whole definition — it's about controllability, not about which engine drives the hydraulics or which one you'd miss more. The AFM/POH-published VMC is determined with the critical engine inoperative.

The left engine is critical on conventional twins, where each engine rotates clockwise as viewed from the pilot's seat (AFH ch. 13).

The reason is P-factor and the moment arm it produces:

• The descending propeller blade of each engine produces greater thrust than the ascending blade when operating under power at positive angles of attack
• The descending blade of the right engine is a greater distance from the CG — a longer moment arm — than the descending blade of the left engine
• So the right engine's thrust acts farther out on the wing

Therefore failure of the left engine produces the most asymmetrical thrust (adverse yaw), because the remaining thrust comes from the right engine, acting on the longer arm (AFH ch. 13, PHAK ch. 2).

Asymmetric loading of the propeller — one of the four left-turning tendencies of a propeller-driven airplane, along with torque reaction, the corkscrew effect of the slipstream, and gyroscopic action (PHAK ch. 5).

At positive angles of attack the descending blade meets the relative wind at a higher effective angle of attack than the ascending blade, so it produces more thrust, and the propeller's thrust center shifts toward the descending-blade side. Multiengine airplanes are subject to P-factor just as single-engine airplanes are (AFH ch. 13).

No — the asymmetry appears when the airplane is operated under power and at positive angles of attack (AFH ch. 13). That's exactly the regime of takeoff and initial climb, which is why the critical engine matters most at the moment it matters most.

Not through the CG — out on the wing, and displaced further by P-factor toward the descending blade side of that propeller disc.

• Right engine operating — descending blade is on the right side of the right propeller, the side farther from the CG. Long arm, large yawing moment
• Left engine operating — descending blade is on the right side of the left propeller, the side nearer the CG. Shorter arm, smaller yawing moment

Longer arm means more yaw for the same thrust. Losing the left engine leaves you fighting the larger moment (AFH ch. 13).

Many twins use a counter-rotating right engine, which removes the critical engine entirely:

• The degree of asymmetrical thrust is the same with either engine inoperative
• No engine is more critical than the other
• A VMC demonstration may be performed with either engine windmilling (AFH ch. 13, PHAK ch. 2)

The descending blades of both propellers end up equidistant from the CG, so neither engine's thrust enjoys the longer moment arm.

No. It still has a published VMC and a red radial line — it simply has no critical engine, because either failure is equally adverse. Everything in the certification-conditions discussion still applies, and losing either engine still costs 80 to 90 percent of climb performance (AFH ch. 13).

Dead foot — dead engine.

In maintaining directional control, rudder pressure is exerted on the side of the airplane with the operating engine. So the foot that isn't working is on the same side as the engine that isn't working (AFH ch. 13).

Identification should be primarily through the control inputs required to maintain straight flight, not the engine gauges — depending on the failure mode, confirmation on the gauges may or may not be possible (AFH ch. 13). Variations on the phrase: "idle foot — idle engine," "working foot — working engine."

Because the recovery from a misidentification is worse than the original failure. The PHAK's case study: a pilot on final assumed a left-engine failure, feathered the good left engine, and set the right at zero thrust — restricting the aircraft to a controlled glide. Realizing he wouldn't make the runway, he added power to both, which caused an enormous yaw to the left with the left propeller feathered, and the aircraft began to turn (PHAK ch. 2).

The first step is identify. There is no shortcut past it.

No — those are systems consequences, and they matter operationally, but they are not what makes an engine critical. The definition is strictly about directional control: the engine whose failure has the most adverse effect on directional control (AFH ch. 13).

That said, know your airplane's systems asymmetries too. On some airplanes with a single engine-driven hydraulic pump, failure of that engine means the only way to raise the landing gear is to allow the engine to windmill or use a hand pump — which the AFH calls not a viable alternative during takeoff, and which can cost hundreds of feet of altitude (AFH ch. 13).

The four (PHAK ch. 5):

1. Torque reaction from engine and propeller
2. Corkscrewing effect of the slipstream
3. Gyroscopic action of the propeller
4. Asymmetric loading of the propeller (P-factor)

Of these, both the AFH's critical-engine discussion and the PHAK's tie the identification of the critical engine specifically to P-factor and the resulting difference in moment arm (AFH ch. 13, PHAK ch. 2). If you offer a longer list on the oral, be ready to defend it — and lead with P-factor, because that is the explanation the handbooks give.

The high-speed rotation of the propeller gives a corkscrew or spiraling rotation to the slipstream. At high propeller speed and low forward speed — takeoff, approaches to power-on stalls — the spiral is very compact and exerts a strong sideward force on the vertical tail, causing a yawing moment about the vertical axis.

As forward speed increases, the spiral elongates and becomes less effective. The corkscrew flow also causes a rolling moment about the longitudinal axis — to the right, while torque reaction's yaw is to the left, so one may partly counteract the other (PHAK ch. 5).

Newton's third law applied to the airplane: as the internal engine parts and propeller revolve one way, an equal force tries to rotate the aircraft the other way. Airborne, this acts about the longitudinal axis, tending to roll the aircraft (PHAK ch. 5).

On the ground during the takeoff roll it adds a yawing moment: as the left side is forced down, more weight is on the left main gear, producing more ground friction on the left tire and a further turning moment to the left (PHAK ch. 5).

Note: most US-built aircraft engines rotate the propeller clockwise as viewed from the pilot's seat — the whole left-turning discussion assumes that (PHAK ch. 5).

The procedure doesn't change; the symmetry does. A VMC demonstration may be performed with either engine windmilling, since the degree of asymmetrical thrust is the same either way (AFH ch. 13).

What does not change: VMC still rises with reduced bank, aft CG, lighter weight, a windmilling propeller, and high power on the operating engine — every certification condition from the VMC section still governs your actual red line (AFH ch. 13).

Slightly, yes — if the airplane is not equipped with counter-rotating propellers, the precise zero-sideslip condition varies slightly with the engine failed, due to P-factor (AFH ch. 13).

The AFH also notes these variations are difficult to detect without more sensitive testing equipment, so the practical target remains the same: roughly 2 degrees of bank toward the operating engine with the ball one-third to one-half out toward it.

• VYSE — best rate of climb with one engine inoperative. Marked with a blue radial line on most airspeed indicators. Above the single-engine absolute ceiling, VYSE yields the minimum rate of sink
• VXSE — best angle of climb with one engine inoperative
• VSSE — safe, intentional one-engine-inoperative speed. The minimum speed at which to intentionally render the critical engine inoperative
• VMC — minimum control speed, red radial line

(AFH ch. 13)

Unless otherwise noted, V-speeds given in the AFM/POH apply to sea level, standard day conditions at maximum takeoff weight. Performance speeds vary with aircraft weight, configuration, and atmospheric conditions (AFH ch. 13).

Speeds may be in mph or knots, and given as CAS or IAS. Newer AFM/POHs generally show KIAS; some V-speeds are stated in KCAS to meet regulatory requirements. Whenever available, operate from published indicated airspeeds (AFH ch. 13).

• All-engine service ceiling — the highest altitude at which the airplane can maintain a steady rate of climb of 100 fpm with both engines operating. Absolute ceiling is where climb is no longer possible
• Single-engine service ceiling — reached when the airplane can no longer maintain a 50 fpm rate of climb with OEI. Single-engine absolute ceiling is where climb is no longer possible

(AFH ch. 13)

The runway length required to accelerate to a specified speed (either VR or VLOF, as specified by the manufacturer), experience an engine failure, and bring the airplane to a complete stop (AFH ch. 13).

The horizontal distance required to continue the takeoff and climb to 50 feet, assuming an engine failure at VR or VLOF as specified by the manufacturer (AFH ch. 13).

No. The regulations do not specifically require that runway length be equal to or greater than accelerate-stop distance. Most AFM/POHs publish accelerate-stop distances only as an advisory — it becomes a limitation only when published in the limitations section of the AFM/POH (AFH ch. 13).

Experienced multiengine pilots nonetheless insist on runway lengths of at least accelerate-stop distance as a matter of safety and good operating practice.

Under ideal circumstances, a point a mere 50 feet above the takeoff elevation — little more than one wingspan above the terrain, assuming it was absolutely level and without obstructions (AFH ch. 13).

And to achieve even that meager climb the pilot had to instantaneously recognize and react to an unanticipated failure, retract the landing gear, identify and feather the correct engine, all while maintaining precise airspeed and bank angle as speed is nursed to VYSE.

As a practical planning matter, the option of continuing the takeoff probably does not exist unless the published single-engine rate-of-climb performance is at least 100 to 200 fpm (AFH ch. 13).

Even 200 fpm can be negated by thermal turbulence, wind gusts, engine and propeller wear, or poor technique in airspeed, bank angle, and rudder control.

At VYSE with maximum available power and minimum drag — meaning flaps and landing gear retracted, the failed engine's propeller feathered, and then the key element: minimizing sideslip (AFH ch. 13).

A windmilling propeller at high speed in the low range of blade angles — near flat pitch — can produce parasite drag as great as the parasite drag of the entire airframe (AFH ch. 13).

At high rpm this can make the airplane difficult or impossible to control. In the feathered position, by contrast, propeller parasite drag is at a minimum — a small part of the airplane's total drag.

If the airplane is above its single-engine absolute ceiling when the failure occurs, it slowly loses altitude. Maintain VYSE to minimize the rate of altitude loss (AFH ch. 13).

The drift-down rate is greatest immediately following the failure and decreases as the single-engine ceiling is approached. Because of performance variations from engine and propeller wear, turbulence, and pilot technique, the airplane may not maintain altitude even at its published single-engine ceiling — though any further rate of sink would likely be modest.

Because turning flight reduces climb performance. Climb should be made straight ahead or with shallow turns to avoid obstacles, to an altitude of at least 400 feet AGL before attempting a return to the airport (AFH ch. 13).

The AFH is blunt in its climb illustration: any turn, such as to return to the airport, seriously degrades the already marginal climb performance of the airplane.

Climb rate: altitude gained per unit of time — unaffected by wind.

Climb gradient: altitude per 100 feet of horizontal travel, expressed as a percentage — affected by wind: improved by a headwind component, reduced by a tailwind component (AFH ch. 13).

Obstacle clearance is a gradient problem.

No. Not all multiengine airplanes have published accelerate-go distances in their AFM/POH, and fewer still publish climb gradients. When such information is published, the figures were determined under ideal flight testing conditions — it is unlikely that this performance is duplicated in service conditions (AFH ch. 13).

With an inoperative engine, a centered ball no longer indicates zero sideslip, because of asymmetric thrust — in fact, no flight deck instrument directly indicates the zero-sideslip condition (AFH ch. 13).

That's different from normal flight: with a single-engine airplane, or a twin with both engines operating, sideslip is eliminated when the ball is centered — the airplane presents its smallest profile to the relative wind and drag is at a minimum. Pilots know this as coordinated flight.

Two control inputs can counteract asymmetric thrust: yaw from the rudder, and the horizontal component of lift from bank. Used individually, neither is correct (AFH ch. 13).

1. Wings level, ball centered — requires large rudder toward the operative engine. Result: a moderate sideslip toward the inoperative engine, reduced climb performance, and VMC significantly higher than published because there is no horizontal component of lift helping the rudder
2. Ailerons alone (no rudder) — requires an 8 to 10 degree bank toward the operative engine, ball displaced well toward the operative engine, and climb performance greatly reduced by the large sideslip. Instructors should not normally demonstrate this
3. Rudder and ailerons together, in the proper combination — approximately 2 degrees of bank toward the operative engine, ball displaced one-third to one-half toward the operative engine. Result: zero sideslip and maximum climb performance

The AFH gives ranges, because it varies by model, power, and airspeed.

Bank angle: varies among airplanes from one and one-half to two and one-half degrees toward the operating engine.

Ball position: one-third to one-half of a ball width from instrument center, toward the operative engine (AFH ch. 13).

These recommendations apply to reciprocating twins flown at VYSE with the inoperative engine feathered. The zero-sideslip ball position for straight flight is also the zero-sideslip position for turning flight.

Because that is how they were flown in testing. The AFM/POH performance charts for one-engine-inoperative flight were determined at zero sideslip, so this technique must be used to obtain the charted OEI performance (AFH ch. 13).

Any attitude other than zero sideslip increases drag, decreasing performance — and whether the airplane can climb at all depends on weight, density altitude, and pilot technique.

A piece of string or yarn approximately 18 to 36 inches long, taped to the base of the windshield or the nose near the windshield along the airplane centerline (AFH ch. 13).

In two-engine coordinated flight the relative wind aligns it with the longitudinal axis — straight up the center of the windshield. That is zero sideslip. With an engine out, a particular combination of aileron and rudder likewise establishes zero sideslip, and the string aligns itself vertically to show it. Maintain adequate altitude, flying speed, and caution if experimenting.

With one engine feathered or set to zero thrust and the airplane slowed to VYSE, climb with maximum power on the remaining engine. That reveals the precise bank angle and ball deflection for zero sideslip and best climb performance (AFH ch. 13).

Zero thrust means power set on one engine such that the drag from its rotating propeller equals that of a stopped, feathered propeller — the standard training substitute for an actual feather.

A controllable-pitch propeller whose pitch is automatically varied in flight by a governor, maintaining constant rpm despite varying air loads (PHAK ch. 7).

• Two controls: the throttle controls power output; the propeller control regulates engine rpm
• Once an rpm is selected, the governor adjusts blade angle to maintain it — an increase in airspeed or decrease in propeller load increases blade angle; a reduction in airspeed or increase in load decreases it
• The constant-speed range is defined by the high and low pitch stops; as long as the blades are within that range and not against a stop, constant rpm is maintained (PHAK ch. 7)

The direction the oil pressure works is reversed.

Most single-engine airplanes: non-feathering, oil-pressure-to-increase-pitch — increased governor oil pressure drives the blade toward high pitch, low rpm.

Most multiengine airplanes: full feathering, counterweighted, oil-pressure-to-decrease-pitch — increased governor oil pressure drives the blade toward low pitch, high rpm, away from feather.

In effect, the only thing keeping these propellers from feathering is a constant supply of high-pressure engine oil. That is deliberate: it enables feathering in the event of a loss of oil pressure or a governor failure (AFH ch. 13).

• Aerodynamic forces on a windmilling propeller tend to drive the blades to low pitch, high rpm
• Counterweights on the blade shanks tend to force the blades to high pitch, low rpm. Inertia acting through the counterweights is generally slightly greater than the aerodynamic forces
• High-pressure governor oil pushes the blades toward low pitch, high rpm

So a reduction in oil pressure allows the counterweights to drive the blades to higher pitch and decreases rpm (AFH ch. 13).

The propeller control is brought fully aft. All oil pressure is dumped from the governor and the counterweights drive the blades toward feather.

As centrifugal force on the counterweights decays with falling rpm, additional force is needed to complete the travel — that comes from either a spring or high-pressure air stored in the propeller dome. The entire process may take up to 10 seconds (AFH ch. 13).

Because of anti-feathering lock pins. Below approximately 800 rpm, a reduction in centrifugal force allows small pins in the pitch-changing mechanism of the hub to move into place and block feathering.

Therefore, if a propeller is to be feathered, it needs to be done before engine rpm decays below approximately 800 (AFH ch. 13). One popular turboprop engine does feather with each shutdown — it has no such centrifugally-operated pins, due to a unique engine design.

Feathering only alters blade angle and stops engine rotation — it stops rotation with the blade streamlined to the relative wind, minimizing propeller drag.

To completely secure the engine you additionally turn off the fuel (mixture, electric boost pump, and fuel selector), the ignition, the alternator/generator, and close the cowl flaps. On a pressurized airplane there may also be an air bleed to close for the failed engine. Some airplanes have firewall shutoff valves that secure several of these with a single switch (AFH ch. 13).

No — completely securing may not be necessary or even desirable, depending on failure mode, altitude, and time available.

The position of the fuel controls, ignition, and alternator/generator switches of the failed engine has no effect on aircraft performance, and the pilot might manipulate the incorrect switch under conditions of haste or pressure (AFH ch. 13). The one exception on that list: closing the cowl flap of the failed engine does affect climb performance.

The engine must be rotated so oil pressure can be generated to move the blades out of feather (AFH ch. 13):

1. Ignition on prior to engine rotation, throttle at low idle, mixture rich
2. Propeller control to a high rpm position
3. Engage the starter — the engine windmills, starts, and runs as oil pressure moves the blades out of feather
4. As the engine starts, immediately reduce propeller rpm until it has had several minutes to warm up; monitor cylinder head and oil temperatures

Always follow the AFM/POH for the exact procedure.

A device that permits starting a feathered engine in flight without the use of the electric starter. It stores a small reserve of engine oil under pressure from compressed air or nitrogen (AFH ch. 13).

Moving the propeller control out of the feather position releases the accumulator pressure; oil flows to the propeller hub and drives the blades toward high rpm, low pitch, whereupon the propeller usually begins to windmill. With fuel and ignition present, the engine starts and runs. High oil pressure from the governor recharges the accumulator just moments after rotation begins, making it available for another cycle. If the accumulator fails to bring the propeller out of feather, the electric starter may be engaged.

A prop sync eliminates the "drumming" or "beat" of propellers whose rpm are close but not precisely the same. The pilot coarsely matches rpm and engages the system, which adjusts the slave engine to precisely match the master engine (AFH ch. 13).

Prop sync should always be off for takeoff, landing, and single-engine operation. Disengage it when selecting a new rpm and re-engage after the new rpm is set.

A synchrophaser goes further — it also compares and adjusts the positions of the individual blades in their arcs, reducing noise and vibration. It is commonly called prop sync, though technically that's imprecise.

Crossfeed lets an engine draw fuel from a tank in the opposite wing. On most multiengine airplanes, crossfeed is an emergency procedure used to extend range and endurance in OEI flight. A few models permit it as a normal fuel-balancing technique, but these are not common (AFH ch. 13).

• Never use crossfeed during takeoff, or for normal landing operations with both engines operating
• Crossfeed is ordinarily not used for completing a flight with one engine inoperative when an alternate airport is nearby
• Prior to landing, terminate crossfeed and return the operating engine to its main tank
• A landing on one engine using crossfeed may be necessary if setting normal fuel flow would cause the operative engine to fail

A quick repositioning of the fuel selectors on the ground does nothing more than ensure freedom of motion of the handle (AFH ch. 13).

A real functional check: during run-up, operate each engine individually from its crossfeed position at moderate power (1,500 rpm minimum) for at least 1 minute to confirm fuel flow can be established from the crossfeed source. Then run each engine at least 1 minute at moderate power from the main (takeoff) tanks to reconfirm fuel flow before takeoff.

This check is not required before every flight, but crossfeed lines are ideal places for water and debris to accumulate unless used from time to time and drained via their external drains during preflight.

Each engine has an alternator or generator. Paralleling circuitry matches the output of each so the electrical load is shared equally.

If one fails, the inoperative unit can be isolated and the entire electrical system powered from the remaining one. Depending on the capacity of the remaining unit, the pilot may need to reduce electrical load — load shedding (AFH ch. 13). The AFM/POH has the system description and limitations.

A small furnace that burns gasoline to produce heated air for cabin comfort and windshield defogging. Most are thermostatically operated with a separate hour meter for maintenance tracking (AFH ch. 13).

Over-temperature protection is a thermal switch that cannot be accessed in flight — resetting it requires a visual inspection of the unit for heat damage. Manufacturers usually specify a cool-down: outside air circulating through the unit for at least 15 seconds in flight, or the ventilation fan for at least 2 minutes on the ground. Failure to cool down usually trips the thermal switch and renders the heater inoperative until reset.

Because it spans the entire range from negligible to airframe-sized (AFH ch. 13).

Feathered: parasite drag from the propeller is at a minimum; in a typical multiengine airplane, a single feathered propeller is a small part of the airplane's total drag.

Near flat pitch, windmilling at high rpm: parasite drag can be as great as the parasite drag of the entire airframe, and enough to make the airplane difficult or impossible to control.

That range is why feathering, done in a timely manner, often permits continued flight to a suitable airport following an engine failure.

Because a windmilling propeller looks like a working one. The AFH names this directly: a windmilling propeller has in many cases given the improperly trained multiengine pilot the mistaken perception that the engine is still developing useful thrust, producing a psychological reluctance to feather — since feathering stops the propeller from turning (AFH ch. 13).

A competent instructor teaches the critical importance of feathering in a timely manner and demonstrates the performance difference between a zero-thrust (simulated feathered) propeller and a windmilling one.

Not necessarily. Not all engine failures result in complete power loss. If there is a performance loss when the throttle of the affected engine is retarded, some power is still available — and the pilot may consider letting it run until reaching a safe altitude and airspeed for single-engine flight (AFH ch. 13).

While shutdown may prevent additional engine damage in some circumstances, shutting down an engine that can still produce partial power may increase risk for an accident. In cruise, leave the engine running if there is any doubt as to needing it for further safe flight.

The exception: catastrophic failure with heavy vibration, smoke, blistering paint, or large trails of oil indicates a critical situation — feather, complete the securing checklist, divert to the nearest suitable airport, and declare an emergency (AFH ch. 13).

No. Both feathering and starting a feathered reciprocating engine on the ground are strongly discouraged by manufacturers due to the excessive stress and vibrations generated (AFH ch. 13).

Similarly, repeated feathering and unfeathering is hard on the engine and airframe, and in training is done only as necessary to ensure adequate training. Plan any unfeathering and restart in training to be complete no lower than 3,000 ft AGL — at some elevations, in many popular trainers, that may be above the single-engine service ceiling, so level flight will not be possible (AFH ch. 13).

Depending on system design, you may need to select between main and auxiliary tanks, or actively transfer fuel from one tank to another. Complex fuel systems often carry limitations restricting some tanks to level flight only, or requiring a reserve in the main tanks for descent and landing (AFH ch. 13).

Electric fuel pump operation varies widely among models, particularly during tank switching or transfer — some pumps are to be on for takeoff and landing, others off. There is no substitute for thorough systems and AFM/POH knowledge.

Sharp turns onto the runway combined with a rolling takeoff are not good practice and may be prohibited by the AFM/POH due to the possibility of "unporting" a fuel tank pickup. The takeoff itself may be prohibited under any circumstances below certain fuel levels (AFH ch. 13).

The same physics limits slips: some multiengine airplanes have AFM/POH limitations against slips in excess of a certain time period — 30 seconds, for example — to prevent power loss from fuel starvation as fuel in the lowered wing's tank flows toward the wingtip, away from the pickup (AFH ch. 13).

By a loss of manifold pressure — not a loss of rpm, which is the fixed-pitch indication (AFH ch. 13).

Select carburetor heat (carbureted) or alternate air (fuel-injected). On some fuel-injected engines the alternate air source is automatically activated when the normal source is blocked.

An increase in manifold pressure to a value corresponding to the ambient air pressure at the altitude where the failure occurred (PHAK ch. 7).

For reference: with the engine not running the gauge indicates ambient pressure (29.92 "Hg at sea level standard); once started, the indication drops below ambient (roughly 12 "Hg at idle). The gauge face carries a green arc for the normal range and a red radial line for the manifold pressure upper limit.

It proves nothing about approval. The presence of anti-ice and deice equipment, however elaborate, does not necessarily mean the airplane is approved for flight in icing conditions — consult the AFM/POH, placards, and even the manufacturer (AFH ch. 13).

Anti-icing prevents ice on protected surfaces: heated pitot tubes, heated or non-icing static ports and fuel vents, propeller electrothermal boots or alcohol slingers, alcohol-spray or electrically heated windshields, defoggers, heated stall warning lift detectors, heated turboprop intake lips.

Deicing removes ice already formed — generally pneumatic boots on wing and tail leading edges, inflated from pneumatic pumps and deflated with vacuum assistance.

Also required for icing flight: alternate induction air, alternate static source, and ice-tolerant antennas. An ice light on the left engine nacelle lets you monitor wing ice at night.

Because continuous use of the autopilot masks trim and handling changes that occur with ice accumulation. Without that control feedback the pilot may not realize ice is building to hazardous levels — and the autopilot suddenly disconnects when it reaches design limits, handing back an airplane with unsatisfactory handling characteristics (AFH ch. 13).

A servo that moves the rudder in response to inputs from a gyroscope or accelerometer detecting yaw rate or lateral G, reducing motion about the vertical axis caused by turbulence (AFH ch. 13).

The yaw damper should be off for takeoff and landing, and there may be additional restrictions against its use with one engine inoperative. Most yaw dampers can be engaged independently of the autopilot.

Latch and lock security is a vital preflight item. When improperly secured, the door may open and the contents may be drawn out — usually into the propeller arc, and usually just after takeoff. Even when the compartment is empty, airplanes have been lost when the pilot became distracted by the open door (AFH ch. 13).

Most airplanes continue to fly fine with a nose baggage door open — some buffeting, more noise. Never become so preoccupied with an open door of any kind that you fail to fly the airplane. Also inspect the interior: tow bars, inlet covers, sun screens, oil containers, chocks, and hand tools accumulate there and must be secured against shifting.

Where your decision point is. The prudent multiengine pilot picks a point in the takeoff and climb sequence in advance (AFH ch. 13).

Before that point: an engine failure means reject the takeoff, even if airborne, landing on whatever runway or surface lies essentially ahead.

After that point: an engine failure means promptly executing the engine failure procedure and continuing the climb, assuming the performance capability exists.

The takeoff should be planned in sufficient detail that the appropriate action is taken, and that decision reviewed as the last item of the before-takeoff checklist.

If the landing gear has not been selected up, reject the takeoff — even if airborne (AFH ch. 13).

Conversely, the general recommendation is to raise the landing gear not later than VYSE, and once the gear is up, consider it a GO commitment if climb performance is available.

Reject. Directional control can only be maintained by promptly closing both throttles and using rudder and brakes as required (AFH ch. 13).

Maintain directional control with rudder, nose-wheel steering, and brakes. The primary objective is not necessarily to stop in the shortest distance, but to maintain control of the airplane as it decelerates — it may be preferable to continue into the overrun under control rather than risk directional control loss, landing gear collapse, or tire/brake failure trying to stop short.

Land (AFH ch. 13):

1. Keep the nose as straight as possible
2. Close both throttles
3. Adjust pitch attitude to maintain adequate airspeed
4. Descend to the runway — concentrate on a normal landing, do not force the aircraft on the ground
5. Land on the remaining runway or overrun

Depending on how quickly you react to the sudden yaw, the airplane may run off the side of the runway by the time action is taken. There are really no other practical options — the chances of maintaining directional control while retracting flaps and gear, feathering, and accelerating are minimal.

Land on whatever essentially lies ahead (AFH ch. 13).

There is also the option of continuing ahead in a descent at VYSE with the remaining engine producing power — as long as you are not tempted to remain airborne beyond the airplane's performance capability.

Remaining airborne and bleeding off airspeed in a futile attempt to maintain altitude is almost invariably fatal. Landing under control is paramount.

Control, configuration, climb, and checklist (AFH ch. 13). In that order — the sequence is the priority list.

Maintaining directional control with prompt and often aggressive rudder application and STOPPING THE YAW is critical to the safety of flight. Ensure airspeed stays above VMC (AFH ch. 13).

• If the yaw cannot be controlled with full rudder applied, reducing thrust on the operative engine is the only alternative
• Attempting to correct the roll with aileron without first applying rudder increases drag and adverse yaw and further degrades directional control
• After rudder stops the yaw, use a slight amount of aileron to bank toward the operative engine
• The pitch attitude for VYSE has to be lowered from that of VY
• Trim to reduce the control forces

Two different numbers, and confusing them costs performance (AFH ch. 13).

Initially: at least 5 degrees, maximum 10 degrees, toward the operative engine, to stop the yaw and establish directional control. This initial bank input is held only momentarily, just long enough to establish or ensure directional control.

Then: reduce to the zero-sideslip bank, because climb performance suffers when bank angles exceed approximately 2 or 3 degrees.

Obtaining and maintaining VYSE and directional control are paramount — you buy control first and performance second.

Rudder and ailerons used together in the proper combination (AFH ch. 13).

Bank: approximately 2 degrees toward the operative engine — the AFH gives a range of one and one-half to two and one-half degrees across models.

Ball: displaced approximately one-third to one-half of a ball width toward the operative engine.

The result is zero sideslip and maximum climb performance. Any other attitude increases drag. Note that VMC under these circumstances is higher than published, since less than the 5-degree certification bank is being used — an accepted trade.

Ball out toward the good engine, wing low toward the good engine, dead engine raised.

Most AFM/POHs direct the pilot to (AFH ch. 13):

1. Assume VYSE
2. Set takeoff power
3. Retract the flaps
4. Retract the landing gear (on some airplanes, gear before flaps)
5. Identify, verify, and feather the failed engine

Follow your AFM/POH and checklist — the specific procedures for your airplane govern.

• Identify — determine which engine failed. Identification should be primarily through the control inputs required to maintain straight flight, not the engine gauges. Depending on the failure mode, gauge confirmation may or may not be possible. Use dead foot — dead engine
• Verify — retard the throttle of the engine you believe has failed. No change in performance when that throttle is retarded is verification that the correct engine has been identified
• Feather — bring the corresponding propeller control fully aft

(AFH ch. 13)

This is not an oversight. The purpose of the memory items is to either initiate the appropriate action or to confirm that a condition exists — action on each item may not be required in every case (AFH ch. 13).

The memory items also apply to more than one circumstance. In an engine failure from a go-around, the landing gear and flaps would likely be extended when the failure occurred.

Differently — because altitude and airspeed buy you time for diagnosis and possible remedy (AFH ch. 13).

Maintaining airplane control is still paramount — airplanes have been lost at altitude due to apparent fixation on the engine problem to the detriment of flying the airplane.

Then take an orderly inventory of gauges and switches. Many cases of power loss are fuel starvation — try selecting another tank. Other options:

• Carburetor heat or alternate air
• Running on just one magneto or a lower power setting
• Altering the mixture
• Boost pump operation, if fuel vapor is suspected, to eliminate flow and pressure fluctuations

When it is catastrophic — a major mechanical failure that damages the engine and precludes further operation. Indicators:

• Heavy vibration
• Smoke
• Blistering paint
• Large trails of oil

Then (AFH ch. 13):

1. Feather the affected engine
2. Complete the securing failed engine checklist
3. Divert to the nearest suitable airport
4. Declare an emergency with ATC for priority handling

Because at low power settings the dramatic yaw and performance loss is absent — the pilot may not even be aware of a failure (AFH ch. 13).

If a failure is suspected, advance both engine mixtures, propellers, and throttles significantly — to the takeoff settings if necessary — to correctly identify the failed engine. The power on the operative engine can always be reduced later.

It clearly defines all pre-planned emergency actions to all crewmembers. Even flying alone, review and be familiar with takeoff emergency considerations — because indecision at the moment an emergency occurs degrades reaction time and the ability to make a proper response (AFH ch. 13).

An emergency contingency plan and safety brief should be clearly understood well before the takeoff roll commences.

Add the takeoff distance to 50 feet AGL and the stopping distance from 50 feet AGL. If the runway is no longer than that total, the odds are very good that if anything fails, it will be an off-runway landing at the least (AFH ch. 13).

Several factors (AFH ch. 13):

• Weight and balance
• Airplane performance (both single- and multiengine)
• Runway length, slope, and contamination
• Terrain and obstacles in the area
• Weather conditions
• Pilot proficiency

Before takeoff, confirm that weight and balance limitations have been observed, runway length is adequate, and the normal flightpath clears obstacles and terrain — then consider the appropriate action in the event of an engine failure at any point during the takeoff.

VMC. On takeoffs, the airplane should never be airborne before the airspeed exceeds VMC (AFH ch. 13).

Use the manufacturer's VR or VLOF. If no such speed is published, use a minimum of VMC plus 5 knots for VR.

Because experience has shown that excessive speed cannot be effectively converted into altitude in the event of an engine failure. After leaving the ground, altitude gain is more important than achieving an excess of airspeed — and additional altitude increases the time available to recognize and respond to any abnormality during the climb segment (AFH ch. 13).

But excessive climb attitudes are just as dangerous: they limit forward visibility and impede your ability to detect and avoid traffic. Accelerate in a shallow climb to VY, and maintain VY until reaching a safe single-engine maneuvering altitude — typically a minimum of 400 to 500 feet AGL (AFH ch. 13).

Because the speeds crowd VMC. VX and VXSE are often perilously close to VMC, leaving scant margin for error in the event of engine failure as VXSE is assumed. If flaps were used for takeoff, the situation becomes even more critical due to the additional drag (AFH ch. 13).

Two specific cautions:

Partial flaps: many light twins have a strong tendency to become airborne prior to VMC plus 5 knots. Preventing this with forward elevator pressure results in wheel barrowing — instead, allow the airplane to become airborne but only a few inches above the runway.

VX close to VMC: if VX is less than 5 knots higher than VMC, give strong consideration to reducing useful load or using another runway, so a short-field technique is not required.

The use of wing flaps for takeoff virtually eliminates the likelihood of a single-engine climb until the flaps are retracted (AFH ch. 13).

Normally, retract when there is insufficient runway available for landing and after a positive rate of climb is established as indicated on the altimeter (AFH ch. 13).

The competing pressures:

• Raising the gear as early as possible after liftoff drastically decreases the drag profile and significantly increases climb performance should an engine fail
• But leaving the gear down to land on sufficient runway or overrun is a much better option than landing with the gear retracted
• The landing gear should remain selected down as long as there is usable runway or overrun available to land on
• In some airplanes at high density altitude, a positive rate of climb with the gear down is not possible — waiting for one is not practicable

None of this justifies retracting the gear the moment the airplane lifts off as a normal procedure.

It gets fuel from a tank on one side to an operating engine on the other, for extended single-engine operation (AFH ch. 13).

• If a suitable airport is close at hand, there is no need to consider crossfeed
• If prolonged single-engine flight is inevitable due to airport non-availability, crossfeed allows use of fuel that would otherwise be unavailable — and lets you balance fuel consumption to avoid out-of-balance wing heaviness
• Prior to landing, terminate crossfeed and return the operating engine to its main tank

AFM/POH crossfeed procedures vary widely; selector positions and boost pump usage differ greatly among airplanes.

Deliberately and without undue haste — unless you suspect an engine fire (AFH ch. 13).

Airplane control should never be sacrificed to execute the remaining checklists. The priority items have already been accomplished from memory, and other than closing the cowl flap of the failed engine, none of the securing items, if left undone, adversely affect airplane climb performance. There is a distinct possibility of actuating an incorrect switch or control if the procedure is rushed.

Concentrate on flying the airplane and extracting maximum performance. If an ATC facility is available, declare an emergency.

Certain immediate action items — such as a response to an engine failure in a critical phase of flight — are best committed to memory. After they are accomplished, and as workload permits, compare the action taken with the checklist (AFH ch. 13).

If there is a procedural discrepancy between a checklist and the AFM/POH, the AFM/POH always takes precedence. Pilots who do not use a checklist effectively will be at a significant disadvantage in multiengine airplanes.

From the AFH (ch. 13):

• Never introduce an engine failure below VSSE. If no VSSE is published, use VYSE. Simulating a failure below VSSE introduces a very high and unnecessary training risk
• All in-flight simulated failures below 3,000 ft AGL should be introduced with a smooth reduction of the throttle, keeping the engine running and available for instant use
• On the takeoff ground roll, a failure may be simulated with the mixture control, introduced at a speed no greater than 50 percent of VMC
• Low-altitude simulated failures normally occur at a minimum of 400 ft AGL, and only after the learner has mastered engine-inoperative procedures at higher altitudes
• Pulling circuit breakers is not recommended for training and can lead to a subsequent gear-up landing
• No simulated engine failures during slow flight — the airplane will be well below VSSE and very close to VMC
• No simulated engine failures during stall entry and recovery

By eliminating ambiguity. When the learner retards a propeller control toward FEATHER, the instructor promptly moves it forward and sets zero thrust, then says words to the effect: "I have the right engine; you have the left. I have set zero thrust and the right engine is simulated feathered" (AFH ch. 13).

Any ambiguity as to who is operating what systems or controls increases the likelihood of an unintended outcome. The instructor then cares for the "failed" engine as the learner cares for the operative one — cowl flap normally closed, mixture leaned, and occasional clearing of the engine.

Structurally, it doesn't — the approach and landing with OEI is essentially the same as a two-engine approach and landing. The traffic pattern should be flown at similar altitudes, airspeeds, and key positions (AFH ch. 13).

The differences are the reduced power available and the fact that the remaining thrust is asymmetrical. A higher-than-normal power setting is necessary on the operative engine.

Yes. The direction of the traffic pattern, and therefore the turns, is of no consequence as far as airplane controllability and performance are concerned — turns toward the failed engine are perfectly acceptable (AFH ch. 13).

Don't distort your pattern to avoid it — flying an awkward pattern to dodge a non-problem creates a real one.

With adequate airspeed and performance, on the downwind leg — confirmed DOWN no later than abeam the intended point of landing (AFH ch. 13).

Performance permitting, an initial flap extension (typically 10 degrees) and a descent from pattern altitude can also begin on downwind. Airspeed should be no slower than VYSE.

Performance decides (AFH ch. 13):

• If performance is adequate — flaps may go to an intermediate setting, typically 25 degrees
• If performance is inadequate — as measured by decay in airspeed or high sink rate — delay further flap extension until closer to the runway

VYSE is still the minimum airspeed to maintain.

Maintain VYSE until the landing is assured, then slow to 1.3 VSO or the AFM/POH recommended speed (AFH ch. 13).

The final flap setting may be delayed until the landing is assured, or the airplane may be landed with partial flaps.

A normal 3-degree glidepath to a landing is desirable. Use VASI or other vertical path lighting aids if available. Slightly steeper approaches may be acceptable (AFH ch. 13).

Avoid a long, flat, low approach and large, sudden power applications or reductions.

Because most light twins do not have the performance to climb on one engine with landing gear and flaps extended (AFH ch. 13).

Considerable altitude is lost while maintaining VYSE and retracting landing gear and flaps — losses of 500 feet or more are not unusual. And if the gear was lowered with an alternate means of extension, retraction may not be possible, virtually negating any climb capability.

Once the airplane is on final approach with landing gear and flaps extended, it is committed to land — on the intended runway, on another runway, a taxiway, or the grassy infield (AFH ch. 13).

That's not a failure of technique; it's the airplane's honest performance. Plan the approach knowing the go-around option is spent.

A rudder trim change as the power of the operating engine is reduced to idle just prior to touchdown (AFH ch. 13).

The airplane should remain in trim throughout the approach — but be ready for that shift at the worst possible moment, close to the ground.

Some pilots reset the rudder trim to neutral on final and compensate for yaw by holding rudder pressure for the remainder of the approach (AFH ch. 13).

This eliminates the rudder trim change close to the ground as the throttle is closed in the round out, and removes the need to grope for the rudder trim and manipulate it during final — which many pilots find highly distracting. Use the AFM/POH recommendation or personal preference.

Because there is drag from only one windmilling propeller instead of two (AFH ch. 13).

Precise airspeed control is therefore essential, especially when landing on a short, wet, or slippery surface.

• Minimal float — higher wing loading plus drag from two windmilling propellers
• Full stall landings are generally undesirable in twins. Hold the airplane off as with a high-performance single, allowing touchdown of the main wheels prior to a full stall
• The pattern and approach are flown at somewhat higher indicated airspeeds — start the before-landing checklist early
• Residual power is gradually reduced to idle in the round out

(AFH ch. 13)

Use the manufacturer's recommended speed with power. If no recommended speed is furnished, the speed should be no slower than VYSE until short final with the landing assured — but in no case less than VMC (AFH ch. 13).

Delaying full flap extension to short final with the landing assured is an acceptable technique with appropriate experience and familiarity with the airplane.

To the greatest extent practical, on final approach and within 500 feet AGL, the airplane should be (AFH ch. 13):

• On speed
• In trim
• Configured for landing
• Tracking the extended centerline of the runway
• Established in a constant angle of descent toward an aim point in the touchdown zone

Absent unusual conditions, only minor corrections should be required from there to round out and touchdown.

Because of higher cruising speed and frequently higher altitude. A hurried, last-minute descent with power at or near idle is inefficient and can cause excessive engine cooling, and may cause passenger discomfort, particularly if unpressurized (AFH ch. 13).

Rule of thumb: if terrain and passenger conditions permit, plan a maximum 500 fpm rate of descent. Pressurized airplanes can plan higher rates if desired.

Some airplanes require a minimum EGT, minimum power setting, or cylinder head temperature in the descent. Combinations of very low manifold pressure and high rpm are strongly discouraged by engine manufacturers — if a higher descent rate is needed, consider extending partial flaps or lowering the landing gear before retarding power excessively.

Sequentially (AFH ch. 13):

1. Throttles to takeoff power, pitch adjusted to arrest the sink rate
2. With adequate airspeed, establish a climb pitch attitude
3. Initial target airspeed VY, or VX if obstructions are present
4. With sufficient airspeed, retract flaps from full to an intermediate position
5. Retract the landing gear when there is a positive rate of climb and no chance of runway contact
6. Retract the remaining flaps

Two reasons (AFH ch. 13): on most airplanes, full flaps produce more drag than the extended landing gear, and the airplane tends to settle somewhat with flap retraction — so the gear should already be down in the event of an inadvertent, momentary touchdown.

• If the airplane was in trim for the landing approach, it soon requires a great deal of forward elevator pressure as it accelerates away in a climb. Apply forward pressure to hold pitch attitude and begin trimming immediately
• Many twins have a landing gear retraction speed significantly less than the extension speed — don't exceed it
• If you return for a landing, re-accomplish the entire before-landing checklist. An interruption to habit patterns such as a go-around is a classic scenario for a subsequent gear-up landing (AFH ch. 13)

The initial pitch-up must be tempered by the necessity to maintain adequate flying speed throughout the maneuver — for example, a go-around from the landing round out, recovery from a bad bounce, or one initiated because of an inadvertent approach to a stall.

The first priority is always to maintain control and obtain adequate flying speed. A few moments of level or near-level flight may be required as the airplane accelerates to climb speed (AFH ch. 13).

The principles are no different from a single. The two primary methods — crab and wing-low — are typically used in conjunction (AFH ch. 13):

• On rolling out onto final, establish the crab angle to track the extended centerline
• Prior to touchdown, transition to a sideslip with the upwind wing lowered and opposite rudder applied to prevent a turn
• Touch down on the upwind main gear first, then the downwind, then the nose gear
• Follow through with increasing aileron into the wind until full deflection is reached

Prior to touchdown, the longitudinal axis must be aligned with the runway centerline to avoid landing gear side loads. Twins are often easier than singles in a crosswind, due to the higher approach and landing speed.

When the upwind wing is lowered, power on the upwind engine is increased to prevent the airplane from turning — the asymmetrical thrust produces a yawing moment little different from the rudder's (AFH ch. 13).

It is completely acceptable, but most pilots feel they can react to changing wind conditions quicker with rudder and aileron than throttle movement — especially with turbocharged engines, where throttle response may lag momentarily. Practice it with an instructor before attempting it alone.

Some multiengine airplanes have AFM/POH limitations against slips in excess of a certain time period — 30 seconds, for example. This prevents engine power loss from fuel starvation as fuel in the lowered wing's tank flows toward the wingtip, away from the pickup point. Observe the limit if using the wing-low method (AFH ch. 13).

The emphasis is on (AFH ch. 13):

• Configuration — full flaps
• A stabilized approach with a constant angle of descent
• Precise airspeed control

Full flaps provide the steepest approach angle. Plan so that no drastic power reductions are required after obstacles are cleared — propeller blast blows over the wings providing lift as well as thrust, so reducing power significantly just after obstacle clearance usually results in a sudden, high sink rate that may lead to a hard landing. Smoothly reduce power to idle in the round out.

Some AFM/POHs recommend a slightly slower than normal approach speed; if none is published, use the normal approach speed.

Under favorable wind and runway conditions, the nose-wheel can be held off for best aerodynamic braking, and continued elevator back pressure greatly assists the wheel brakes even after the nose-wheel is gently lowered (AFH ch. 13).

But it's undesirable to rely solely on aerodynamic braking if:

• Runway length is critical
• There's a strong crosswind
• The surface is contaminated with water, ice, or snow

Place the full weight of the airplane on the wheels as soon as practicable — the wheel brakes are more effective than aerodynamic braking alone.

Generally no. Flap retraction on the rollout is discouraged unless there is a clear operational need, and it should not be accomplished as routine with each landing (AFH ch. 13).

Short field, high winds, or strong crosswinds are just about the only situations where it should be considered. When there is an operational need, do it deliberately, with the flap handle positively identified before it is moved — there is always a significant risk of retracting the landing gear instead of the wing flaps.

Ordinarily, make no attempt to retract flaps or perform other checklist duties until the airplane is stopped clear of the active runway. Never reach out indiscriminately for any switch or control on rollout.

No — the concept is no different than that of a single-engine airplane. The execution, however, is almost invariably more complex (AFH ch. 13).

The new loading areas: nose and aft baggage compartments, nacelle lockers, main fuel tanks, auxiliary fuel tanks, nacelle fuel tanks, and numerous seating options across a variety of interior configurations. That flexibility places a responsibility on the pilot to address weight and balance prior to each flight.

standard empty weight + optional equipment = basic empty weight — GAMA's standardized terms, adopted in 1975 and implemented by most manufacturers starting model year 1976 (AFH ch. 13):

• Standard empty weight — the standard airplane, full hydraulic fluid, unusable fuel, and full oil
• Optional equipment — the weight of all equipment installed beyond standard
• Basic empty weight — standard empty weight plus optional equipment. Includes no usable fuel, but full oil

Pre-GAMA airplanes generally use (AFH ch. 13):

empty weight + unusable fuel = standard empty weight

standard empty weight + optional equipment = licensed empty weight

Here empty weight is the standard airplane, full hydraulic fluid, and undrainable oil.

The major difference between the two formats: basic empty weight includes full oil and licensed empty weight does not. Oil should always be added to any weight and balance utilizing a licensed empty weight.

Because when the airplane is placed in service, amended documents are prepared by rated maintenance personnel to reflect equipment changes — and maintenance personnel are under no regulatory obligation to utilize the GAMA terminology (AFH ch. 13).

Superseded documents are customarily marked "superseded" and retained in the AFM/POH. Use care to determine whether oil has to be added to the calculation or is already included.

The maximum allowable weight of the airplane and payload, assuming there is no usable fuel on board (AFH ch. 13). The actual airplane isn't devoid of fuel at loading, of course — it's a calculation that assumes it was.

If a zero fuel weight limitation is published, then all weight in excess of that figure should consist of usable fuel.

Its purpose: to limit load forces on the wing spars with heavy fuselage loads. Fuel in the wings relieves those forces; payload in the fuselage adds to them. Not all multiengine airplanes publish a zero fuel weight, but many do — the twin is where most pilots meet the term for the first time.

• Useful load — the maximum combination of usable fuel, passengers, baggage, and cargo the airplane can carry. Maximum takeoff weight minus basic empty weight
• Payload — the maximum combination of passengers, baggage, and cargo the airplane can carry. A zero fuel weight, if published, is the limiting weight

(AFH ch. 13)

• Ramp weight — a weight in excess of maximum takeoff weight, allowing for fuel burned during taxi and run-up so a takeoff can be made at full maximum takeoff weight. The airplane should weigh no more than maximum takeoff weight at the beginning of the takeoff roll
• Maximum landing weight — a limitation against landing above the published value. This requires preflight planning of fuel burn to ensure arrival weight is at or below it

(AFH ch. 13)

Land — but understand what you're spending. The structural margins designed into the airplane are not fully available when over landing weight. An overweight landing inspection may be advisable; consult the service manual or the manufacturer (AFH ch. 13).

The flight characteristics of a multiengine airplane vary significantly with shifts of the CG within the approved envelope (AFH ch. 13):

Forward CG — more stable, slightly higher stalling speed, slightly slower cruising speed, favorable stall characteristics

Aft CG — less stable, slightly lower stalling speed, slightly faster cruising speed, less desirable stall characteristics

Forward CG limits are usually determined in certification by elevator/stabilator authority in the landing round out. Aft CG limits are determined by the minimum acceptable longitudinal stability.

VMC increases as the CG is moved aft. The moment arm of the rudder is reduced, and therefore its effectivity is reduced, as the CG moves aft. For a typical light twin, the aft-most CG limit is the most unfavorable CG position (AFH ch. 13, 23.149(b)).

This is why VMC is certificated at the most unfavorable CG — and why an aft-loaded airplane has a higher actual red line than the one painted on the ASI.

VMC increases as weight is reduced (AFH ch. 13).

It is emphatically not good news, because the same lighter weight that raises VMC also improves single-engine climb. Light training twins can therefore have deceptively good single-engine performance combined with a higher actual VMC — the AFH notes most multiengine training is conducted in four-to-six place airplanes at weights significantly below maximum, where single-engine performance, particularly at low density altitudes, may be deceptively good.

Yes. Some multiengine airplanes require ballast to remain within CG limits under certain loading conditions (AFH ch. 13):

• Several models require ballast in the aft baggage compartment with only a learner and instructor on board, to avoid exceeding the forward CG limit
• When passengers occupy the aft-most seats of some models, ballast or baggage may be required in the nose baggage compartment to avoid exceeding the aft CG limit

When ballast is added, it must be securely tied down and must not exceed the maximum allowable floor loading.

No — it is contrary to the airplane's operating limitations and to 14 CFR to exceed any weight and balance parameter (AFH ch. 13). It's a regulatory violation, not a judgment call.

Work it from the handbook's own figures rather than memorizing a constant: 800 lb of fuel is stated as 133.3 gallons, and 180 gallons is stated as 1,080 lb (AFH ch. 13). Both give 6 lb per gallon for avgas.

Always use the weight per gallon your AFM/POH specifies for the fuel grade you're actually carrying.

Nose baggage compartment, aft baggage compartment, nacelle lockers, main fuel tanks, auxiliary fuel tanks, and nacelle fuel tanks — plus many seating configurations (AFH ch. 13).

Each is a separate arm on the loading form, and the nose and nacelle stations sit at very different moment arms from anything on a single-engine trainer. The nose compartment in particular can swing the CG forward hard, which is exactly why some models use it as ballast for aft-loaded passengers.

Two, and both have killed people (AFH ch. 13):

1. Security of the latches and locks. When improperly secured the door may open and contents may be drawn out — usually into the propeller arc, and usually just after takeoff. Even when empty, airplanes have been lost when the pilot became distracted by the open door
2. Inspection of the interior. More than one pilot has been surprised to find a supposedly empty compartment packed to capacity or loaded with ballast. Tow bars, inlet covers, sun screens, oil containers, spare chocks, and hand tools must be secured to prevent damage from shifting in flight

A device with several movable parts adjusted over a plotting board on which the CG envelope is printed. A pencil line plot can be made directly on the envelope, erased, and recalculated for each flight. The reverse side typically contains general loading recommendations for that airplane (AFH ch. 13).

It is to be used only for the make and model airplane for which it was designed.

From the certification conditions and performance discussion (AFH ch. 13):

The uncomfortable conclusion: there is no loading that optimizes both. A light, aft-loaded training twin has good single-engine climb and a raised actual VMC. A heavy twin has a lower actual VMC and may have no single-engine climb at all.

Forward CG has one clear safety benefit worth naming: flying with a CG closer to the forward limit provides better stall and spin avoidance characteristics — though the AFH is careful to add that it does not eliminate the hazard (AFH ch. 13).

Because the majority of multiengine training is conducted in four-to-six place airplanes at weights significantly less than maximum, where single-engine performance — particularly at low density altitudes — may be deceptively good (AFH ch. 13).

To show the performance you'd actually see at higher weights, altitudes, and temperatures, an instructor may artificially limit the manifold pressure available on the operative engine; airport operations above the single-engine ceiling can be simulated the same way.

What an instructor should not do: load the airplane with passengers to practice emergencies at maximum takeoff weight — the AFH calls that an unnecessary training hazard.

As the first of the AFH's takeoff planning factors: weight and balance, airplane performance (both single- and multiengine), runway length, slope and contamination, terrain and obstacles, weather conditions, and pilot proficiency (AFH ch. 13).

Prior to takeoff, ensure that weight and balance limitations have been observed, the runway length is adequate, and the normal flightpath clears obstacles and terrain — then decide what you'll do if an engine quits at any point during the takeoff.

An applicant for an additional class rating must (61.63(c)):

1. Have a logbook or training record endorsement from an authorized instructor attesting that you were found competent in the appropriate aeronautical knowledge areas and proficient in the appropriate areas of operation
2. Pass the practical test

That's the whole list. AMEL is a class rating within the airplane category — you already hold the category.

No — you need not take an additional knowledge test, provided you hold an airplane, rotorcraft, powered-lift, weight-shift-control aircraft, powered parachute, or airship rating at that pilot certificate level (61.63(c)(4)).

You already hold an airplane rating at your certificate level, so the written is behind you.

No specified training time. An applicant for an additional class rating need not meet the specified training time requirements prescribed by this part that apply to the pilot certificate for the aircraft class rating sought (61.63(c)(3)).

The one exception in the rule: a person who holds only a lighter-than-air category rating with a balloon class rating and is seeking an airship class rating must meet the specified training time and aeronautical experience.

Practically, "no minimum" is not "no training." The standard you must meet is your instructor's competence-and-proficiency endorsement and the practical test — and the discipline this rating demands is not measured in hours.

A category rating additionally requires that you complete the training and have the applicable aeronautical experience (61.63(b)(1)). A class rating carries no such specified training time (61.63(c)(3)).

Both require the instructor endorsement and the practical test, and neither requires an additional knowledge test if you already hold an airplane, rotorcraft, powered-lift, weight-shift-control, powered parachute, or airship rating at that certificate level (61.63(b), (c)).

The multiengine tasks of the ACS appropriate to the certificate level you hold — the Private Pilot ACS if you hold a private certificate, the Commercial Pilot ACS if you hold a commercial. You are not earning a new certificate; you are adding a class rating to the one you have.

The ACS for a multiengine class rating contains a task for feathering and unfeathering of one propeller during flight in airplanes in which it is safe to do so (AFH ch. 13). Get the current ACS for your certificate level and read its multiengine areas of operation directly.

A type rating is required for (61.31(a)):

• Large aircraft (except lighter-than-air)
• Turbojet-powered airplanes
• Powered-lift
• Other aircraft specified by the Administrator through aircraft type certificate procedures

Most light twins fall well below those thresholds — an AMEL class rating covers them. The AFH's whole chapter concerns airplanes of 12,500 lb or less maximum certificated takeoff weight (AFH ch. 13).

For an aircraft type rating you must meet all of the following (61.63(d)(1)–(4)):

1. Hold or concurrently obtain an appropriate instrument rating (except as provided in paragraph (e))
2. Be endorsed as competent and proficient at the airline transport pilot certification level
3. Pass the practical test at the ATP certification level
4. Perform the practical test in actual or simulated instrument conditions (except as provided in paragraph (e))

See the next card for what (e) allows.

If you provide an aircraft not capable of the required instrument maneuvers and procedures, the rating will be issued limited to "VFR only" (61.63(e)).

Three takeoffs and three landings within the preceding 90 days, as sole manipulator of the flight controls, in an aircraft of the same category, class, and type (if a class or type rating is required) (61.57(a)(1)).

Category and class are the operative words. Your currency in a single-engine airplane does not carry over to a multiengine airplane — AMEL is a different class. Landings in your twin likewise do not make you current in the single.

The same three takeoffs and three landings within the preceding 90 days, but to a full stop, during the period beginning 1 hour after sunset and ending 1 hour before sunrise — and again in an aircraft of the same category, class, and type (if a class or type rating is required) (61.57(b)).

So night currency in a twin requires full-stop landings in a twin.

Yes. For the purpose of meeting 61.57(a)(1), a person may act as PIC under day VFR or day IFR provided no persons or property are carried on board other than those necessary for the conduct of the flight (61.57(a)(2)).

Note the exception applies to the general (day) experience paragraph — go re-read 61.57(b) before assuming the same for night.

Instrument recent experience under 61.57(c)(1) is by category, not class: within the 6 calendar months preceding the month of the flight, performed and logged in an airplane (or powered-lift, helicopter, or airship as appropriate):

• Six instrument approaches
• Holding procedures and tasks
• Intercepting and tracking courses through the use of navigational electronic systems

So instrument currency earned in a single-engine airplane satisfies 61.57(c) for airplanes generally. Legal is not the same as proficient — single-engine instrument currency prepares you poorly for an OEI approach in a twin.

A person who has failed to meet the 61.57(c) instrument experience requirements for more than six calendar months may reestablish currency only by completing an instrument proficiency check (61.57(d)(1)).

The IPC must cover the areas of operation in the applicable ACS as listed in appendix A of part 61, must be in an aircraft appropriate to the aircraft category (or a representative full flight simulator or FTD), and must be given by an examiner, an authorized instructor, or the other authorized persons listed in 61.57(d)(3).

A class rating is not always enough — 61.31 adds one-time endorsements by airplane characteristic, not by class:

• Complex airplane — ground and flight training from an authorized instructor, found proficient in the operation and systems, plus a one-time logbook endorsement (61.31(e))
• High-performance airplane — defined as an airplane with an engine of more than 200 horsepower — same training plus a one-time endorsement (61.31(f))
• Pressurized aircraft capable of operating at high altitudes — defined as an aircraft with a service ceiling or maximum operating altitude, whichever is lower, above 25,000 feet MSL — requires both logged ground training with an endorsement and logged flight training with an endorsement (61.31(g))

Most light twins are complex and high-performance, so expect at least two of these.

The rating itself doesn't, but your ability to use it is gated by the usual requirements:

• A flight review
• An appropriate medical or BasicMed
• The 61.57 recent experience above for carrying passengers

Beyond the regulations, the AFH's own framing applies: the performance and redundancy of a twin only increase safety if the pilot is trained and proficient (AFH ch. 13). Currency is a legal floor; proficiency in a twin is a separate, higher, and perishable thing.

Because of the OEI regime. The AFH: there are several unique characteristics of multiengine airplanes that make them worthy of a separate class rating, and the OEI flight information emphasizes the significant difference between flying a multiengine and a single-engine airplane (AFH ch. 13).

But note the handbook's own caveat in the same paragraph: all pilots need appropriate knowledge, risk management strategies, and skills to fly safely in any airplane they fly, and mastery of OEI flight is only one aspect of safe multiengine flying.

An examiner who conducts your practical test may waive any task for which the FAA has provided waiver authority (61.63(i)).

This is the hook the FAA uses for tasks that cannot be safely accomplished in a given airplane or under given conditions — for example, the AFH notes the ACS feathering task applies in airplanes in which it is safe to do so (AFH ch. 13). Don't plan on a waiver; know what your airplane and the day permit and brief it with the examiner.

An applicant for a type rating, at other than the ATP certification level, in a multiengine airplane with a single-pilot station must perform the practical test in the multi-seat version of that airplane — or in the single-seat version if the Examiner is in a position to observe the applicant during the practical test and there is no multi-seat version of that airplane (61.63(f)).

Pull the current ACS for the certificate level you hold and work its multiengine areas of operation directly — those tasks are the test. The multiengine-specific ones (AFH ch. 13):

• VMC demonstration
• Engine failure during takeoff and in flight
• Engine-inoperative approach and landing
• Feathering and unfeathering where safe to do so

Pair each task with the AFM/POH numbers for your airplane. The ACS tells you what; the AFM/POH is the final authority on how, and the manufacturer's guidance takes precedence over any general recommendation (AFH ch. 13).

Two things (AFH ch. 13):

The airplane as a procedures trainer. Many normal, abnormal, and emergency procedures can be introduced and practiced in the airplane as it sits on the ground without the engines running — the value of this training may be substantial, and the engines do not have to be operating for real learning to occur. Restore all items to their proper positions afterward.

Simulation. For maneuvers that would be hazardous in flight, or for initial and recurrent qualification in an advanced multiengine airplane, consider a simulator training center or manufacturer's training course. Emergency procedures that would be dangerous or impossible to accomplish in an airplane can be done safely and effectively in an FTD or simulator — and the device need not duplicate the specific make and model to be useful.

It calls the practice somewhat controversial, and comes down against it early on (AFH ch. 13):

• The learning value may be offset by the hazards of reconfiguring the airplane for takeoff in extremely limited time, and the loss of the follow-through of a full-stop landing
• Touch-and-goes are not recommended during initial aircraft familiarization in multiengine airplanes
• The multiengine airplane uses considerably more runway for a touch-and-go than a single
• A full stop-taxi back landing is preferable during initial familiarization
• Solo touch-and-goes in twins are strongly discouraged

If done at all, learner and instructor responsibilities must be carefully briefed prior to each flight — typically the learner maintains directional control with left hand on the yoke and right hand on the throttles while the instructor resets flaps and trim and announces when the airplane is reconfigured.

Two things, before the flight begins (AFH ch. 13): the objectives, maneuvers, expected learner actions, and completion standards, and a clear understanding of how simulated emergencies will be introduced and what action the learner is expected to take.

The reason is stark: surprising a multiengine learner with an emergency without a thorough briefing beforehand creates a hazardous condition, and stall-spin accidents in training for emergencies rival the number of stall-spin accidents from actual emergencies.

The rating is the beginning of the obligation, not the end. The chapter's closing argument: a competent multiengine pilot acquires the additional knowledge, risk mitigation strategies, and practical skills required to fly the airplane in case a loss of thrust actually occurs (AFH ch. 13).

Practical implications:

• Keep your AFM/POH numbers current in memory — VMC, VYSE, VXSE, VSSE, single-engine ceiling
• Keep the memory items for engine failure after takeoff genuinely memorized
• Recognize that 61.57 currency in a twin is class-specific — single-engine landings don't count
• Treat simulator recurrent training as the normal way to rehearse what cannot be safely flown

Non-regulatory note — practical guidance, not a 14 CFR requirement: insurance carriers typically impose their own minimums for make and model time, dual received, and recurrent training. Those requirements come from the underwriter, not the FAA — get them in writing from your broker before you plan a checkout.