Aircraft General Knowledge – Airframe, Systems, Electrics, Powerplant and Emergency Equipment
This domain tests the systems knowledge a CPL holder needs to recognise normal and abnormal indications, not to certify maintenance. Expect airframe structures, hydraulics, electrical supply, fuel, piston or turbine powerplant, and emergency equipment.
Airframe and systems
- Semi-monocoque structures carry flight loads through skin, stringers and frames; inspect for cracks, corrosion and loose fasteners in walk-around questions.
- Hydraulic systems: identify reservoir, pump, pressure relief, selector and actuator. A pressure drop with normal quantity suggests pump or relief-valve trouble, not necessarily a leak.
- Fuel: know tank selection, primer, mixture, boost pump and fuel drains. Water and sediment drain before the first flight of the day.
Electrics and powerplant
- The battery supplies starting and emergency power; the alternator/generator carries the main bus in flight. A discharge indication with a failed alternator means load shedding.
- Piston engine: magneto checks, carburettor icing, mixture at altitude, and cylinder-head temperature limits. Turbine: start limits, EGT/ITT and N1/N2 indications.
Emergency equipment
- Fire bottle, first-aid kit, ELT, life jackets, exits and crash axe. Know stowage, operation and inspection intervals from the aircraft documentation.
Worked example
In cruise the ammeter shows discharge and the alternator warning is on. The battery is supplying the bus. Reduce non-essential load (pitot heat if not needed, landing light, cabin accessories), keep radio and transponder, and plan to land before battery endurance is exhausted. Do not reset a tripped alternator field breaker repeatedly.
Traps
Confusing alternator and battery roles; assuming a hydraulic pressure drop always means leakage; forgetting that emergency gear extension may require speed reduction; mixing volts, amps and ampere-hours.