Aircraft General Knowledge: Airframes, Engines and Systems
Core concepts
Understand the airframe (structure, control surfaces, load paths), powerplant (reciprocating or turbine, induction, ignition, fuel, cooling, lubrication), and systems (electrical, hydraulic, pneumatic, fuel, ice protection, pressurisation). Know how carburettor ice forms, how mixture affects power and temperature, and the function of the constant-speed propeller and its governor.
Traps
- Carburettor ice can form at outside air temperatures well above freezing (roughly −10 °C to +25 °C with high humidity); questions test the temperature band.
- Detonation vs pre-ignition: detonation is uncontrolled rapid burning after normal ignition; pre-ignition is ignition before the spark.
- Electrical questions: know bus bar, alternator/generator, and what happens on alternator failure (battery only, limited time).
- Hydraulic system: understand accumulator purpose and system redundancy.
Worked example
Mixture leaning: as altitude increases, air density falls, so the mixture becomes richer. Rule of thumb: lean to peak EGT then enrich slightly for cruise; at high density altitude, an over-rich mixture causes rough running and power loss.
Study tip
Draw a block diagram of each system (fuel, electrical, hydraulic) and label failure points; questions often ask what remains available after a failure.