Aircraft General Knowledge - Airframe, Systems and Powerplant
This domain tests the aircraft as an integrated machine: structure, hydraulics, pneumatics, electrical power, fuel, pressurisation, flight controls, landing gear and brakes, ice and rain protection, and turbine powerplant operation. Questions often ask what remains available after a system failure, so learn systems by source, consumer and backup.
Airframe and systems
- Semi-monocoque structure carries pressurisation loads through skin, frames and stringers; repeated pressurisation cycles drive fatigue and corrosion inspection.
- Hydraulics: reservoir, engine-driven pump, accumulator, pressure-relief valve, selector valve and actuator. A failed pump may leave an accumulator for limited braking or alternate gear extension.
- Electrical: DC buses, transformer-rectifier units, batteries, integrated drive generators and bus ties. Know which bus is lost when a generator trips.
- Pneumatics: bleed air supplies pressurisation, anti-ice and engine starting. Valve position and duct pressure matter more than the nominal source.
- Fuel: tanks, boost pumps, crossfeed and imbalance control; jettison only if fitted and approved.
- Powerplant: N1, N2 and EPR indications, FADEC fuel metering, ignition, starting, thrust reversers and fire detection/extinguishing.
Worked example
A left hydraulic low-pressure warning appears in climb. First confirm fluid quantity and pump operation. If pressure is genuinely lost, isolate the system, use the approved alternate gear extension and remember that brake accumulators give only a limited number of applications. Do not repeatedly reset a failed pump.
Traps
Confusing AC and DC buses, TRUs and static inverters; assuming bleed air is always available; mixing EPR with N1; forgetting that a fire bottle has a limited discharge; and treating an alternate system as unlimited.