Aircraft General Knowledge: Airframe, Systems and Powerplant
Aircraft General Knowledge: Airframe, Systems and Powerplant covers structural loads, flight controls, hydraulics, pneumatics, electrical, fuel, ice and rain protection, fire protection, pressurization, landing gear, and piston or turbine engine operation. The exam tests system purpose, normal indications, failure consequences and limitations.
Core rules
- Primary structure carries limit and ultimate loads; limit load must not cause permanent deformation, and ultimate load must not cause failure.
- Hydraulic systems use pressure times area to produce force; redundancy may come from multiple pumps, accumulators and power transfer units.
- Electrical buses are split for redundancy; essential and emergency buses feed critical instruments and radios.
- Fuel systems manage feed, transfer, venting and jettison where fitted; imbalance and unuseable fuel are limitations.
- Turbine engines are monitored by EGT, N1/N2, fuel flow and oil pressure/temperature; exceedances require checklist action.
Worked example
A hydraulic piston has area 0.01 m2 and system pressure 200 bar. Since 200 bar equals 20,000,000 Pa, force = pressure times area = 20,000,000 times 0.01 = 200,000 N, or 200 kN. If pressure falls to 100 bar, force halves to 100 kN for the same piston.
Traps
- Mixing gauge and absolute pressure.
- Assuming a system remains fully available after one pump failure.
- Confusing N1 and N2, or EGT limits with start limits.
- Ignoring unuseable fuel and tank imbalance limits.