Engine starting procedure
| Stage | Item | Requirement | Reason |
|---|---|---|---|
| Pre-start check | Fuel | Physical check of tanks, not gauges alone | - |
| Pre-start check | Tank air vents | Open, unobstructed | Else fuel cannot flow at the rate the engine needs |
| Pre-start check | Fuel caps | Secure | Loose cap can let airflow syphon tank empty rapidly in flight |
| Siting | Propeller slipstream | Point away from hazards: hangar door, parked aircraft, crowd | - |
| Siting | Ground | Start on firm, smooth turf or concrete, not loose ground | Slipstream blows stones and dirt back into aircraft or property behind |
| Siting | Taxiway | Do not block a taxiway | - |
| Prestart cockpit check | Brakes | On and secure | Else aircraft can move forward unexpectedly |
| Prestart cockpit check | Mixture, fuel selector | No start attempt with mixture in idle cut-off or fuel selector off | Repeated attempts just discharge battery |
Primer:
- Draws filtered fuel, sprays it directly into intake ports. Useful when cold weather hinders vaporization.
- Use only as the Aircraft Flight Manual specifies.
- After priming: push knob full in, rotate past lock notch. Unlocked primer lets engine keep drawing fuel through priming system: over-enriched mixture, roughness or failure.
- Overpriming raises fire risk during start.
- Overpriming in cold weather: backfire and carburettor fire if engine does not start (TP 1102).
- Overpriming also common in summer; little or no priming often required (TP 1102).
Cold-weather start (warm cold engine before start; AFM/POH sets own figures):
| Situation | Cause | Action |
|---|---|---|
| Preheat | Cold engine | Direct warm air into engine cowling inlets behind the propeller; open flames prohibited near airplane |
| Failed start below 0 °C (C172S POH) | Combustion moisture can freeze on spark plugs if engine does not keep running after firing; blocks next start | Preheat before next attempt |
| Winter operations: cold oil (TP 1102) | Oil is thick: oil drag | Ignition off, mixture idle cut-off: turn propeller by hand several revolutions. Easier start, less load on starter and battery |
| Fuel spilled on snow or ice (TP 1102) | Gasoline evaporates more slowly than usual on cold surface; engine exhaust flame could ignite it | Move aircraft a safe distance from spill before starting engine |
Trap: unlocked primer is not minor: engine siphons extra fuel on its own, over-richening mixture; vibration can work an unlocked primer loose, causing malfunction.
References
- TP 1102 Aeroplane Flight Training Manual, Engine Handling: Prior to Starting, Aircraft Engine Primers, Starting
- TP 1102 Aeroplane Flight Training Manual, Ex.2 Aircraft Familiarization, Flight Preparation
- TP 1102 Aeroplane Flight Training Manual, Ex.22 Forced Landing
- TP 1102 Aeroplane Flight Training Manual, Ex.29 Emergency Procedures
- Cessna 172S POH Supplement 18, Normal Procedures: Cold Soak (example aircraft)
- TP 1102 Aeroplane Flight Training Manual, Skiplanes: Operations
- TP 1102 Aeroplane Flight Training Manual, cold oil and starting