Demonstration of Effects of Various Airspeeds and Configurations during Engine Inoperative Performance (AMEL and AMES)

To make the student feel what each configuration item and each airspeed costs on one engine, so that the engine-out checklist stops being a memorized list and becomes a set of understood trades.

The AFH assigns this squarely to you: "A competent flight instructor teaches the multiengine learner about the critical importance of feathering the propeller in a timely manner... The flight instructor should spend ample time demonstrating the difference in the performance capabilities of the airplane with a simulated feathered propeller (zero thrust) as opposed to a windmilling propeller" (AFH 13-36).

The evaluator must assess all three Tasks in Area XIII, so this one is not optional — and it is the Task where you prove you can teach cause and effect rather than procedure.

High, and higher than you think. Three constraints stack:

• The ACS floor — the evaluator "must select an entry altitude that will allow the single-engine demonstration Tasks to be completed no lower than 3,000 feet AGL or the manufacturer's recommended altitude (whichever is higher)" (ACS Appendix 2, Multiengine Considerations).
• The maneuver consumes altitude. Every configuration you demonstrate produces a sink rate, and you will demonstrate several in sequence. Budget the loss before you start, not after.
• If you feather for real, do it "at altitudes and positions where safe landings on established airports may be readily accomplished if the propeller will not unfeather," with unfeathering and restart complete no lower than 3,000 feet AGL (AFH 13-36).

Below 3,000 feet AGL, engine failure is simulated by reducing the throttle to idle and then establishing zero thrust (ACS Appendix 2).

Establish the reference condition first, so every later change is measured against a known baseline:

1. Clear the area, note the altitude and heading, and brief what is coming.
2. Slow to VYSE in the clean configuration, gear and flaps up.
3. Simulate the failure with a smooth throttle reduction to idle, then set zero thrust — the power setting at which drag from the rotating propeller equals that of a stopped, feathered propeller (AFH 13-29).
4. Stop the yaw with rudder, then bank about 2° toward the operating engine with the ball one-third to one-half toward that engine — zero sideslip (AFH 13-29).
5. Maximum available power on the operating engine, and trim.
6. Note the vertical speed. That number is the baseline. Write it on the kneeboard.

Everything after this is one change at a time, back to baseline in between.

Both directions cost you, and the student needs to see both.

Above VYSE: climb rate falls off as excess thrust horsepower is spent on parasite drag. VYSE is by definition "best rate of climb speed with OEI" (AFH 13-1), so any other speed is worse.

Below VYSE: climb rate falls off faster, because induced drag climbs steeply and the airplane is heading for the back side of the power-required curve. And you are now walking toward VMC, where the trade is no longer performance but control.

Above the single-engine absolute ceiling, VYSE "yields the minimum rate of sink" (AFH 13-1) — so blue line is the right answer whether you are climbing or drifting down (AFH 13-34).

Demonstrate ±10 knots from blue line and let the VSI make the argument.

A windmilling propeller near flat pitch can add as much parasite drag as the entire airframe — this is the headline of the whole Task. As the AFH puts it: "At the smaller blade angles near the flat pitch position, the drag added by the propeller is large. A propeller windmilling at high speed in the low range of blade angles can produce parasite drag as great as the parasite drag of the entire airframe" (AFH 13-3).

By contrast, "when the propeller blade angle is in the feathered position, parasite drag from the propeller is at a minimum. In a typical multiengine airplane, the parasite drag from a single, feathered propeller is a small part of the airplane's total drag" (AFH 13-3).

Fly it back to back — zero thrust, note the VSI; windmilling at the same speed and power, note the VSI again — and let the difference land. This is the antidote to the "psychological reluctance to feather" the AFH warns about (AFH 13-36).

The performance cost is the obvious part: extending the gear on one engine typically converts whatever marginal climb existed into a descent, which is exactly why the memory items call for gear up and why "raising the landing gear as early as possible after liftoff drastically decreases the drag profile and significantly increases climb performance should an engine failure occur" (AFH 13-16).

The surprise is the handling change: extended landing gear aids directional stability, which tends to decrease VMC (AFH 13-25). So the configuration that hurts your performance the most actually improves your controllability. Name that trade out loud — it is the cleanest example in the airplane of why VMC and VYSE are two different problems.

Also teach the decision rule: with the gear selector still DOWN after a failure on takeoff, continued flight is not recommended (AFH 13-33).

Flaps alone: the AFH's blunt version — "The use of wing flaps for takeoff virtually eliminates the likelihood of a single-engine climb until the flaps are retracted" (AFH 13-33). Extend the takeoff setting at VYSE and let the student watch the VSI move.

Gear and flaps together: this is the landing configuration, and it is the condition in which "a single-engine go-around on final approach may not be possible." Most light twins "do not have the performance to climb on one engine with landing gear and flaps extended," and losses of 500 feet or more are not unusual while retracting them and holding VYSE (AFH 13-35).

Teach the operational conclusion, not just the number: once on final on one engine with gear and flaps out, the airplane is committed to land — "on the intended runway, on another runway, a taxiway, or grassy infield" (AFH 13-35).

As the cheapest performance you will ever buy. Three cases, all flyable at VYSE with zero thrust set (AFH 13-28 to 13-29):

1. Wings level, ball centered — large rudder input toward the operating engine, moderate sideslip toward the inoperative engine, reduced climb. And VMC is significantly higher than published, because there is no horizontal lift component helping the rudder.
2. Ailerons alone, no rudder — requires 8–10° of bank toward the operating engine, ball well out toward the good engine, and climb performance "greatly reduced by the large sideslip." Because of the increased risk of loss of control, "instructors should not normally demonstrate this" (AFH 13-28).
3. Both in the proper combination — about 2° of bank, ball one-third to one-half out toward the operating engine: zero sideslip and maximum climb performance. Say the paired caveat out loud, because it is the whole point of this Task: "VMC under these circumstances is higher than published, as less than the 5° bank certification limit is employed" (AFH 13-29).

Demonstrate 1 and 3. Describe 2. And name the trade case 3 makes: zero sideslip buys the best climb the airplane has, and it pays for it with control margin — which is why VYSE, not the red line, is the speed you hold there.

Change one thing, name it, quantify it, undo it:

1. "Zero thrust set, blue line, zero sideslip. Baseline: one hundred feet per minute up."
2. "Gear coming down. Nothing else changes — same speed, same power, same bank. Read me the VSI."
3. "Gear up. Back to baseline. Confirm."
4. "Flaps to takeoff. Read the VSI."
5. "Flaps up. Baseline."
6. "Now speed. Ten knots slow of blue line, same configuration. Read it. Ten fast. Read it."
7. "Last one — I'm going from zero thrust to a true windmill. Watch that needle."

"The instructor avoids extraneous activity as much as possible so that learners get a clear understanding of the task" (AIH 9-5). One variable at a time is what makes this Task teach anything.

• Airspeed control is the experiment's control variable. If the speed drifts while you change configuration, the demonstration proves nothing. Anticipate the pitch change before each gear or flap selection.
• Smooth inputs (AI.XIII.C.S2). Abrupt configuration changes on one engine produce sink rates that require an aggressive recovery — and the student learns the wrong lesson about how much margin exists.
• Maintain the appropriate airspeed, attitude, and altitude combinations for each configuration (AI.XIII.C.S3) — VYSE remains the floor for every configuration you demonstrate.
• Retrim as the configuration changes so control forces do not mask what the airplane is telling you.
• Finish by returning to normal cruise flight at the altitude and heading the evaluator specifies (AI.XIII.C.S4).

• Changing two things at once — gear plus a speed change. Nothing is learned. Correction: reset to baseline and repeat the single change.
• Letting airspeed wander while configuring, so the VSI change can't be attributed to the configuration.
• Starting too low, then rushing the last configurations or busting the 3,000-foot floor (ACS Appendix 2).
• Abrupt gear or flap selections and the sink rate that follows.
• Failing to narrate — the ACS requires the applicant to "demonstrate, describe, and explain" (AI.XIII.C.S1). Silent flying fails this Task even if the airplane is flown perfectly.
• Losing zero sideslip during a configuration change, so the drag measured includes the pilot's own sloppiness (AFH 13-29).
• Fixating inside and dropping the traffic scan (AI.XIII.C.R5).

• Speed floor is VYSE. When you demonstrate below blue line, do it briefly and never approach VMC — every configuration change is being made with asymmetric power at low airspeed, which is the setup the AFH names for spin awareness: "any condition of high asymmetrical thrust, particularly at low speed/high AOA" (AFH 13-18).
• No simulated engine failures during slow flight — "the airplane will be well below VSSE and very close to VMC" (AFH 13-18).
• The gear and flap cycle is a real commitment. On some airplanes with a single engine-driven hydraulic pump, failure of that engine means the gear can only be raised by windmilling the engine or hand-pumping (AFH 13-30).
• Any stall symptom terminates the demonstration. Reduce AOA first (AFH 13-18).
• Your take-the-controls trigger: airspeed below blue line and decaying, or the ball departing while the student is looking at the gear handle.

Artificially limit power. "To experience the performance expected at higher weights, altitudes and temperatures, the instructor may occasionally artificially limit the amount of manifold pressure available on the operative engine. Airport operations above the single-engine ceiling can also be simulated in this manner" (AFH 13-36).

What you must not do: "Avoid loading the airplane with passengers to practice emergencies at maximum takeoff weight, since this practice creates an unnecessary training hazard" (AFH 13-36).

Brief the limit before you fly it, and say what real-world condition it represents — a July departure at a high-elevation airport, four aboard and full fuel. Otherwise the student concludes the airplane is worse than it is, which is its own bad lesson.

Because Task XIII.A trains a procedure and this Task builds the judgment underneath it. The AFH's three engine-failure-after-takeoff scenarios all turn on a single question — is single-engine climb performance adequate? — and the answer depends entirely on configuration and airspeed (AFH 13-30 to 13-32).

"The greatest hazard in a single-engine takeoff is attempting to fly when it is not within the performance capability of the airplane to do so. An accident is inevitable" (AFH 13-30). And the data back it: "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. Analysis also reveals a very high fatality rate in stall spin accidents when the pilot attempts flight beyond the performance capability of the airplane" (AFH 13-30).

A student who has felt the gear come down on one engine makes that decision differently.

Directly — that's the transfer of learning. After the flight, have the student rewrite their pre-takeoff safety brief using the numbers they just recorded.

The AFH's planning standard: continuing the takeoff "probably does not exist as an option unless the published single-engine rate-of-climb performance is at least 100 to 200 fpm," and "thermal turbulence, wind gusts, engine and propeller wear, or poor technique in airspeed, bank angle, and rudder control can easily negate even a 200 fpm rate of climb" (AFH 13-12).

Their brief should now name a decision point — "an engine failure before this point results in an aborted takeoff; after this point, with the gear up and climb performance assured, the appropriate engine failure procedure and continued climb" (AFH 13-12). The general rule they should say out loud: if the landing gear has not been selected up, the takeoff should be rejected, even if airborne (AFH 13-12).

Collaborative, not a lecture. Start with learner self-assessment — "the purpose of the self-assessment is to stimulate growth in the learner's thought processes and, in turn, behaviors" — then compare it against your assessment (AIH 9-6).

Three questions worth asking in order:

1. "Which single change cost the most, and were you expecting that one?"
2. "Given today's numbers, at what point on our departure runway would you have continued?"
3. "What would you have to change about the airplane or the day to make continuing a reasonable choice?"

Then close on the standard: they will be held to altitude ±100 feet or minimum sink rate, airspeed ±10 knots, headings ±10° when they fly OEI maneuvering (AI.XIII.A.S7). Offer concrete suggestions where performance fell short, and "if possible, avoid ending the evaluation on a negative note" (AIH 9-6).