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Commercial pilot · ACS CA.II.C · lesson pack

Engine Starting

Why this one matters

Propeller strikes are among the most preventable injuries in aviation, and a botched start can damage an expensive engine. On the ramp with passengers and line staff nearby, a disciplined start protects people first and the engine second.

1 · Know these cold

  • •Follow the POH start procedure for the condition: normal, cold, hot, flooded, and, for fuel-injected engines, the specific hot-start technique.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • •Look around, turn on the beacon, call "Clear!" and wait before engaging the starter.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • •Treat every propeller as live: a broken magneto ground wire can let the engine fire when the propeller is moved.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • •Oil pressure must rise within the POH time limit: typically about 30 seconds in normal weather, and up to about twice that in very cold weather, when the oil is thick. If it hasn't risen by the POH limit for the conditions, shut down.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations; Your airplane's POH/AFM)
  • •Respect starter duty limits: they vary widely (10-second bursts in some types, 30 seconds with minutes of cooling in others). Know your airplane's numbers and follow them.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations; Your airplane's POH/AFM)
  • •External power: connect a ground power unit only as the POH describes, at the right voltage, and disconnect before taxi.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • •Position the airplane so the propeller blast won't hit people, aircraft or buildings, and not over loose gravel.(Commercial Pilot ACS (FAA-S-ACS-7B), CA.II.C.S1)

2 · The lesson

Starting in different conditions
  • Normal start: by the checklist; brakes set or held, master on, beacon on, fuel pump and mixture as the POH says, "Clear!", starter, with one hand on the throttle to catch a surge. After start, set the POH idle (often about 1,000 RPM), don't let it race, and check oil pressure first, then the charging system and the other indications.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • Cold weather: preheat below the temperature the manufacturer specifies; cold oil is thick and batteries are weak.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • Hot fuel-injected engine: fuel vaporizes in the lines (vapor lock). The hot-start procedure is specific to the engine and airframe: many purge vapor with the fuel pump at idle cutoff; some crank at idle cutoff and advance the mixture only as it fires. Don't prime it like a cold or carbureted engine; use your POH's exact sequence.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • Flooded engine: usually mixture idle cutoff and throttle open while cranking, then mixture rich as it fires, per the POH.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • External power: when the battery is weak, a ground power unit can start the engine. Use the POH procedure and correct voltage, and have the unit disconnected and clear before taxi.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
Limits and when to stop
  • Crank for the POH time limit, then let the starter cool; repeated long cranking overheats it.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • No oil pressure within the POH time (often about 30 seconds; in very cold weather the POH may allow up to about 60, because cold oil is slow): shut down.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • If the starter stays engaged after the engine starts, shut down.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • Engine fire during start, as the POH directs: keep cranking to draw the flames in while cutting off the fuel (mixture idle cutoff, throttle open, fuel pump and selector off). If it starts, run it briefly, then shut down and inspect. If it doesn't, or the fire persists, stop cranking, finish the POH fire procedure, get everyone out, fight it from outside, and don't try another start.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations; Your airplane's POH/AFM)
Propeller safety
  • Never move a propeller casually: a broken P-lead means a magneto isn't grounded and can fire the engine with the switch off.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)
  • Brief passengers to stay clear of the propeller arc when boarding and leaving, and never start with someone near the airplane.(Commercial Pilot ACS (FAA-S-ACS-7B), CA.II.B.S2)
  • Hand-propping is never done alone: two trained people who both know the airplane and the technique, one pulling the propeller and calling the steps, the other at the controls, who knows them thoroughly, with the brakes set and the airplane chocked or tied down. Agree the calls ("fuel on, switch off, throttle closed, brakes set"; "contact") before starting.(Airplane Flying Handbook (FAA-H-8083-3C), Ground Operations)

Want it all on one page, with scenarios? Read the full lesson.

On the flight

ACS standards

  • Position the airplane considering structures, other aircraft, wind, and the safety of people and property nearby; complete the checklists.(Commercial Pilot ACS (FAA-S-ACS-7B), CA.II.C.S1-S2)

What your instructor is watching for

Your instructor watches for a real look around and a loud "Clear!", brakes held, oil pressure checked right after start, and the correct technique for a hot fuel-injected engine.

3 · Say it out loud

Answer each one out loud, then check yourself and mark how it went.

  1. Remember Recall it

    “What do you check immediately after the engine starts?”

  2. Understand Explain why

    “Why is a hot fuel-injected engine hard to start?”

  3. Apply Use it on a flight

    “After a quick fuel stop on a hot day, the engine won't start with a normal procedure. What do you do?”

4 · Common mistakes

  • Using a carburetor-style start on a hot fuel-injected engine.

    It floods or vapor-locks the engine and overheats the starter.

    Instead: Learn the POH hot-start procedure for that airplane.

  • Calling "Clear!" without looking.

    People near the propeller may be outside your quick glance.

    Instead: Look all around, call, and wait before engaging the starter.

  • Ignoring a weak battery after a ground-power start.

    It may mean a charging-system fault.

    Instead: Watch the ammeter after start and have it checked if charging is abnormal.

5 · Quick check

Answer, then reveal. Flag anything you want to see again.

  1. 1. What is vapor lock?

  2. 2. Why are starter cranking times limited?

  3. 3. Why treat the propeller as live with the magnetos off?

  4. 4. What must be done with a ground power unit before taxi?

  5. Scenario5. You see smoke from the cowling during start. What does the POH usually say to do first?

Trained it? Now prove it: practice engine starting out loud with our examiner.

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Connect it

One situation that runs across this lesson and its neighbors in the same ACS area. Decide first, then check.

Connect it · Preflight Procedures

A retractable-gear airplane with a constant-speed propeller. During preflight you find fresh hydraulic fluid near the nose gear. Three passengers are boarding.

How do the preflight finding, the passenger briefing and the before-takeoff check connect? Decide, then see the worked answer

Stop the boarding and keep the passengers clear of the airplane until a mechanic has inspected the fresh fluid near the gear and you, as PIC, have determined the airplane is airworthy. A failed gear system changes every landing. Once it's cleared, review the POH emergency gear-extension procedure before departure: a check on the ground proves only that the gear is down and indicating down now. Brief the passengers as 91.107 requires: how to fasten and unfasten their seat belts and, where installed, shoulder harnesses, and that they must be fastened for movement on the surface, takeoff and landing. Add the exits and emergency equipment. Confirm the down-and-locked indications in the preflight, and check them again before takeoff per the POH. The run-up is for cycling the propeller and checking the engine instruments; it tells you nothing about how the gear will work in flight.

AFH (FAA-H-8083-3C), Transition to Complex Airplanes; 14 CFR 91.7, 91.107

Brings together: Preflight Assessment · Flight Deck Management · Before Takeoff Check

Teaching this? The instructor lesson plan →

Study aid, not FAA guidance. Sources: Airplane Flying Handbook (FAA-H-8083-3C); Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C); Risk Management Handbook (FAA-H-8083-2A); Commercial Pilot ACS (FAA-S-ACS-7B); Your airplane's POH/AFM. Checked against current sources 2026-11-13.