Aircraft General Knowledge (Airframe, Systems, Engines, Instruments)
Aircraft General Knowledge
This domain covers the airframe, flight controls, piston powerplant, fuel, electrical, hydraulic and pneumatic systems, and the pitot-static and gyroscopic instruments. The exam expects system purpose, normal indications and failure consequences, not memorised diagrams.
Core rules
- A four-stroke piston engine runs induction, compression, power and exhaust. Magnetos provide independent ignition; a magneto check confirms both circuits and detects fouling.
- Carburettor icing can occur at ambient temperatures up to about 20°C with high humidity; apply carburettor heat and expect a power change.
- The pitot-static system drives the ASI, altimeter and VSI. A blocked pitot affects airspeed; a blocked static source affects altitude and climb indications.
- Gyroscopic instruments depend on rigidity and precession. The heading indicator must be reset to the magnetic compass periodically.
Worked example
An aircraft is parked at an aerodrome elevation of 1,600 ft with QNH 1000 hPa. With 1013 hPa set on the subscale, the altimeter reads pressure altitude: 1,600 + (1013 - 1000) × 30 = about 1,990 ft. Set to QFE, it should read 0 ft at the parking position. The reasoning is that 1 hPa is approximately 30 ft near the surface.
Traps
QFE reads height above the aerodrome reference point, not altitude. The ASI measures dynamic pressure, not static pressure. A heading indicator is not a magnetic instrument. Do not assume a high EGT always means high power; use the POH.