Run-up procedure: fuel, carb heat, and full power
Run-up: pre-takeoff engine ground check, at Aircraft Flight Manual (AFM) RPM.
- Magneto check (RPM drop, differential limit): see
aeronautics/engine-ignition. Rest of sequence below.
Fuel tanks:
- If a tank change is planned, do it before the run-up, not during the take-off roll; fuel-system malfunction then shows on the ground, not airborne.
Carburettor heat check (at AFM RPM, or magneto-check RPM if none given):
- Select full cold, note RPM.
- Select full hot, note RPM decrease, let it stabilize.
- Select cold again, note RPM increase.
| Result | Meaning |
|---|---|
| No RPM decrease on hot | Suspect malfunction |
| RPM on return to cold higher than first cold reading | Carburettor icing conditions exist, extra care needed |
Carb heat on the ground:
- Use cold while taxiing or during sustained ground running, unless AFM says otherwise.
- Hot bypasses the air intake filter, letting sand and debris into the carburettor.
Full power check:
- Most run-ups no longer include a static full-power check, so nothing in the normal run-up proves full power.
- Normally confirmed on the take-off roll.
- Short-field take-off: static full-power check before the aircraft moves, if the surface allows.
Trap: finishing the run-up does not guarantee full power; the take-off roll normally proves it.
References
- TP 1102 (Flight Training Manual), Engine Handling: Run-up, Carburettor Heat Check, Full Power Check