Task X.A
Maneuvering with One Engine Inoperative
To determine the applicant exhibits satisfactory knowledge, risk management, and skills associated with maneuvering with one engine inoperative.
Note: See Appendix 2: Safety of Flight and Appendix 3: Aircraft, Equipment, and Operational Requirements & Limitations for information related to this Task.
References: FAA-H-8083-2, FAA-H-8083-3, FAA-H-8083-25; FAA-P-8740-66; POH/AFM
Study Notes
AMEL/AMES task. At altitude, with time to work the problem: identify, verify, feather, secure — then troubleshoot and restart.
Identify: dead foot, dead engine — the leg doing no rudder work points at the failed engine.
Verify: retard that engine's throttle; no change confirms it.
Feather: pull the correct prop control fully aft into feather (past the detent).
Secure: for the dead engine — mixture cutoff, fuel selector off, boost pump off, magnetos off, alternator off, cowl flap closed — per the POH checklist (AFH ch 13, POH).
The reason it quit — fuel, air, spark: switch tanks, boost pump on, mixture adjust, carb heat/alternate air, check mags. Many "failures" are fuel starvation and come right back. The ACS specifically wants me to attempt to determine and resolve the cause when altitude and time allow (ACS X.A S4).
A windmilling propeller is a huge flat-plate drag source that also drives the dead engine, and it can cost most of the remaining climb performance. Feathering aligns the blades with the airflow, stopping rotation and cutting drag dramatically — it's the highest-value drag reduction available (AFH ch 13).
Zero sideslip: bank 2–5° into the operating engine, ball roughly half-deflected toward the good engine, and trim it. Fly VYSE (blue line) for best climb or minimum sink.
ACS tolerances here:
- Altitude: ±100 ft (or minimum sink if unable)
- Airspeed: ±10 kt
- Heading: ±10° (AFH ch 13, ACS X.A S7)
Follow the manufacturer's unfeathering procedure — typically:
- Fuel selector on, boost pump on, mixture set.
- Prop control forward, out of feather.
- Crank with the starter, or use the unfeathering accumulator if equipped.
The prop windmills, the engine fires, and I warm it at low power before bringing it back into service. Airspeed helps the prop come out of feather (AFH ch 13, POH).
Practice it at altitude with a recovery floor, plus:
- Honor VSSE as the minimum speed for intentionally failing an engine.
- Monitor the operating engine's temperatures and pressures — it's working hard.
- Maintain situational awareness for traffic and terrain while heads-down in checklists (ACS X.A R2–R5, ACS Appendix 2).
Official ACS elementsreference
Knowledge5 elements
The applicant demonstrates understanding of:
PA.X.A.K1Factors affecting minimum controllable speed (VMC).PA.X.A.K2VMC (red line) and best single-engine rate of climb airspeed (VYSE) (blue line).PA.X.A.K3How to identify, verify, feather, and secure an inoperative engine.PA.X.A.K4Importance of drag reduction, including propeller feathering, gear and flap retraction, the manufacturer's recommended control input and its relation to zero sideslip.PA.X.A.K5Feathering, securing, unfeathering, and restarting.
Risk Management5 elements
The applicant is able to identify, assess, and mitigate risk associated with:
PA.X.A.R1Potential engine failure during flight.PA.X.A.R2Collision hazards.PA.X.A.R3Configuring the airplane.PA.X.A.R4Low altitude maneuvering, including stall, spin, or controlled flight into terrain (CFIT).PA.X.A.R5Distractions, task prioritization, loss of situational awareness, or disorientation.
Skills8 elements
The applicant exhibits the skill to:
PA.X.A.S1Recognize an engine failure, maintain control, use manufacturer’s memory item procedures, and use appropriate emergency procedures.PA.X.A.S2Set the engine controls, identify and verify the inoperative engine, and feather the appropriate propeller.PA.X.A.S3Use flight controls in the proper combination as recommended by the manufacturer, or as required to maintain best performance, and trim as required.PA.X.A.S4Attempt to determine and resolve the reason for the engine failure.PA.X.A.S5Secure the inoperative engine and monitor the operating engine and make necessary adjustments.PA.X.A.S6Restart the inoperative engine using manufacturer’s restart procedures.PA.X.A.S7Maintain altitude ±100 feet or minimum sink rate if applicable, airspeed ±10 knots, and selected headings ±10°.PA.X.A.S8Complete the appropriate checklist(s).