Inflight Powerplant(s) Failure and Restart (AMEL, AMES)

• Airspeed: ±10 knots
• Altitude: ±100 feet
• Headings: ±10°

These apply as specified by the evaluator and within the airplane's capability (VII.D S6).

That last clause matters. If the airplane cannot hold altitude on the remaining engine at your weight and altitude, the standard becomes the best performance available — you are expected to fly the drift-down correctly, not to conjure climb performance that does not exist. Say so out loud when it applies; the ACS anticipates it.

Under altitude protection. Appendix 2 requires that Tasks involving powerplant shutdown or propeller feathering be performed only under conditions and at a position and altitude where it is possible to make a safe landing on an established airport if there is difficulty restarting or unfeathering. The evaluator must select an entry altitude that allows the powerplant failure Tasks to be completed no lower than 3,000 feet AGL or the manufacturer's recommended altitude, whichever is higher (FAA-S-ACS-11A, Appendix 2).

If it turns out not to be possible to restart the powerplant or unfeather the propeller while airborne, the applicant and the evaluator should treat the situation as an emergency (Appendix 2).

It depends on the airplane and on your history. From Appendix 2:

• Except for a type rating practical test, in a propeller-equipped airplane (including turboprop) the applicant must feather one propeller and shut down an engine unless the manufacturer prohibits it
• If the applicant has not previously demonstrated multiengine tasks for the commercial certificate, they may not use a propeller-equipped airplane whose manufacturer prohibits feathering for an initial ATP multiengine certificate
• If the test is conducted in an airplane requiring a type rating, the applicant may perform a simulated powerplant failure — and in that case, per Appendix 3, a restart procedure must be considered for the given scenario and a simulated restart should be performed if applicable to the airplane design and the scenario
• In all other cases, the applicant must feather and unfeather the propeller while airborne

In an FSTD, feathering or shutdown may be performed in conjunction with any Task and at locations and altitudes at the evaluator's discretion (Appendix 3).

Diagnose first, and let the diagnosis pick the branch. AFH ch. 13 draws the line clearly:

• Not catastrophic — many power losses are related to fuel starvation, where power may be restored simply by selecting another tank. An orderly inventory of gauges and switches may reveal the problem. Alternate air can be selected, the engine may run smoothly on one magneto or at a lower power setting, altering the mixture may help, and boost pump operation may eliminate flow and pressure fluctuations if fuel vapor is suspected.
• Catastrophic — heavy vibration, smoke, blistering paint, or large trails of oil indicate a critical situation. Feather the affected engine, complete the securing checklist, divert to the nearest suitable airport, and declare an emergency with ATC for priority handling (AFH ch. 13).

And the judgment call in between: "the engine should be left running if there is any doubt as to needing it for further safe flight" (AFH ch. 13). A precautionary shutdown of a partially producing engine is a decision to give away thrust you may want.

Because on one engine, the airplane's entire performance reserve is spent on drag you can eliminate. Until it is feathered, the propeller of the failed engine is windmilling, producing a great deal of drag and yawing tendency (AFH ch. 13). The same logic governs gear and flaps.

The priority list for controllability and performance:

1. Stop the yaw
2. Clean up the airframe
3. Feather
4. Trim to zero sideslip

Everything after that is bookkeeping. VII.D S3 grades it as "use flight controls in the proper combination as recommended by the manufacturer, or as required to maintain best performance, and trim as required."

Time and energy. "Engine failures well above the ground are handled differently than those occurring at lower speeds and altitudes. Cruise airspeed allows better airplane control and altitude, which may permit time for a possible diagnosis and remedy of the failure" (AFH ch. 13).

The trap that comes with that time is fixation: "Maintaining airplane control, however, is still paramount. Airplanes have been lost at altitude due to apparent fixation on the engine problem to the detriment of flying the airplane" (AFH ch. 13). In a crew airplane the antidote is structural — one pilot flies and nothing else, the other troubleshoots, and the assignment is spoken.

If the airplane is above its single-engine absolute ceiling when the failure occurs, it will slowly lose altitude. Maintain the engine-out best rate of climb speed to minimize the rate of altitude loss. The drift-down rate is greatest immediately following the failure and decreases as the single-engine ceiling is approached (AFH ch. 13).

Two cautions from the same source: because of performance variations caused by engine and propeller wear, turbulence, and pilot technique, the airplane may not maintain altitude even at its published single-engine ceiling — though any further sink would likely be modest. And in transport-category operations, the drift-down profile and the terrain-clearance escape route are part of the dispatch plan, so ATC needs to know your intentions and your level-off altitude early.

Crossfeed is a method of getting fuel from a tank on one side of the airplane to an operating engine on the other, used for extended single-engine operation (AFH ch. 13). The decision rule is simple:

• A suitable airport close at hand — no need to consider crossfeed
• Prolonged single-engine flight is inevitable because no airport is available — crossfeed allows use of fuel that would otherwise be unavailable to the operating engine, and it lets you balance consumption to avoid out-of-balance wing heaviness

Two disciplines: AFM/POH crossfeed procedures vary widely — selector positions and boost pump usage differ greatly among multiengine airplanes, so thorough fuel system knowledge is essential. And prior to landing, terminate crossfeed and return the operating engine to its main tank supply (AFH ch. 13).

You might not. "An engine failure in a descent or other low power setting can be deceiving. The dramatic yaw and performance loss is absent. At very low power settings, the pilot may not even be aware of a failure" (AFH ch. 13).

The diagnostic technique: 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 (AFH ch. 13). Do this before you are configured, slow, and low.

The ACS says select the nearest suitable airport or landing area (VII.D S8), and under part 121 that is a rule, not a preference: whenever an engine fails or is shut down to prevent possible damage, the PIC must land at the nearest suitable airport, in point of time, at which a safe landing can be made (121.565(a)).

The only relief is for airplanes with three or more engines losing not more than one, where the PIC may proceed to a selected airport after reasonably concluding it is as safe as landing at the nearest suitable one, weighing:

• The nature of the malfunction
• Altitude, weight, and usable fuel at shutdown
• Weather en route and at possible landing points
• Air traffic congestion
• Terrain
• Familiarity with the airport

(121.565(b)). That decision generates a written report to the director of operations (121.565(d)), and the shutdown itself must be reported to the appropriate communication facility as soon as practicable (121.565(c)).

Use the control cue first and confirm with instruments — the reverse of the instinct. AFH ch. 13 directs that identification be made "primarily through the control inputs required to maintain straight flight, not the engine gauges," because confirmation on the gauges may or may not be possible depending on the failure mode. Then verify by retarding the throttle of the suspect engine: no change in performance confirms the identification.

At altitude and low power the yaw may be subtle, which is why advancing all power levers to re-establish an asymmetry is a legitimate diagnostic step (AFH ch. 13). In a crew airplane, both pilots must agree aloud before any lever moves — a confirmed-and-challenged shutdown is the whole point of two-crew procedure, and shutting down the wrong engine is the accident this task exists to prevent.

Memory items are the small set of actions that must happen before there is time to read — typically confirming the failure, securing a fire, or preventing the failure from propagating. The ACS expects them completed "if applicable" (VII.D S1), and Appendix 2 acknowledges that when reading the actual checklist is impractical or unsafe, the evaluator assesses your immediate-action memory items along with your review of the appropriate checklist once conditions permit.

Then VII.D S2 takes over: coordinate with crew and complete the appropriate emergency procedures and checklists for propeller feathering or powerplant shutdown. Run them deliberately. The AFH's counsel applies at altitude even more than after takeoff: unless a fire is suspected, remaining items should be accomplished "deliberately and without undue haste," and "airplane control should never be sacrificed to execute the remaining checklists" (AFH ch. 13).

It requires you to notice that the surviving engine is now doing a job it was not sized to do alone, often at a high power setting for a long time. Watch and manage:

• Temperatures — ITT/TIT, CHT, and oil temperature climb with sustained high power and reduced airspeed; cowl flaps, mixture, or a small speed increase are the levers
• Time limits — takeoff and maximum continuous power ratings carry AFM time limits; know which rating you are using and for how long
• Fuel — the operating engine is burning from one side; crossfeed for balance on a long diversion, and terminate it before landing (AFH ch. 13)
• Electrical and pneumatic load — with one generator and one bleed source, load shedding may be required before you need the hydraulics on approach

The examiner's version of this question is usually "how long can you hold that power setting?" The answer is in the AFM limitations section, and it is type-specific.

Because control forces on one engine are high enough to degrade everything else you have to do. AFH ch. 13 notes that after the initial rudder input, "control forces, particularly on the rudder, may be high," and that trim should be adjusted to lower them. An untrimmed airplane on one engine gives you a slow drift in heading, a creeping sideslip that costs climb performance, and a pilot whose leg is tiring during the exact phase where a precise approach is about to be required.

Trim to zero sideslip — the AFM's technique where published, otherwise a small bank toward the operating engine with the slip/skid ball displaced one-third to one-half toward the good engine (AFH ch. 13). Then re-trim after each configuration or power change.

• Appropriate — when the cause is understood and benign, altitude and time permit, and the AFM's restart envelope is satisfied. Turbine restart envelopes are bounded by altitude and airspeed — there is a windmilling relight range and, usually, a starter-assisted range with a lower ceiling. Get inside the envelope before pushing a button.
• Inappropriate — when the failure was catastrophic, when there is any indication of fire or fuel leak, when the cause is unknown and the airplane is flying acceptably on the remaining engine, or when you are close enough to a suitable airport that the restart adds risk without adding options. A relight of an engine that failed for a mechanical reason can produce a fire you did not have a moment ago.

The ACS wording gives you room to reason: "consider a powerplant restart and, if appropriate, demonstrate the powerplant restart procedures in accordance with the manufacturer or operator specified procedures and checklists" (VII.D S7). Saying "I would not attempt a restart, and here is why" is a passing answer when the reasons are sound.

Six threads, each with a concrete mitigation:

• Diagnosis of the cause (R3) — an inventory of gauges and switches before touching anything; confirm before you secure
• Configuring the airplane (R5) — drag is the enemy; gear and flaps stay up until the landing is assured
• Inadvertent stall, spin, and loss of control (R6) — the single-engine minimum control speed and the engine-out climb speed are floors, not targets; the accident record for engine failures is dominated by loss of control, not by the failure itself (AFH ch. 13)
• Collision hazards (R4) — you are maneuvering off the airway, possibly descending in a drift-down, often distracted; ask ATC for traffic and keep one pilot looking outside in VMC
• Distractions and task prioritization (R7) — the fixation warning from AFH ch. 13: airplanes have been lost at altitude because the crew worked the problem instead of flying
• Methods for handling the failure or restart (R2) — follow the manufacturer's or operator's procedure; improvised sequences are how the wrong engine gets secured