Aircraft General Knowledge
Airframe and systems
A CPL candidate must understand the load paths and the purpose of primary and secondary structure: spars, ribs, stringers, frames, and skin carry flight and landing loads. Know the difference between fail-safe and safe-life design, and why damage tolerance matters on transport aircraft. Systems knowledge should cover hydraulic, pneumatic, electrical, fuel, and pressurisation systems at a functional level: what drives them, what protects them (fuses, circuit breakers, relief valves), and what happens on failure.
Powerplant
For piston engines, know the four-stroke cycle, the role of the mixture control, detonation versus pre-ignition, and why carburettor icing occurs at temperatures well above freezing. For turbine engines, know the compressor, combustion, and turbine sections, and the meaning of EGT, N1, N2, and ITT limits.
Electrics
Understand the alternator/generator, battery, bus bar, and the significance of a failed alternator (load shedding). Know that the battery is a limited reserve and that essential bus items are protected.
Traps
- Confusing detonation (explosive, uncontrolled burn) with pre-ignition (ignition before the spark).
- Thinking carburettor icing only happens near 0 °C; the risk band is roughly -10 °C to +20 °C with high humidity.
- Mixing N1 (fan/low-pressure spool) and N2 (high-pressure spool) indications.
- Assuming a failed alternator means immediate loss of all electrical power; the battery provides reserve.
Worked example
If EGT rises abnormally with a fixed power setting and the engine runs rough, suspect detonation: reduce power, enrich the mixture, and lower the cylinder head temperature. This is a classic question sequence.