Aircraft General Knowledge
Core concepts
This domain covers airframe, powerplant, systems, and instruments. You must understand the four-stroke cycle, carburettor icing, fuel and oil systems, electrical generation and distribution, hydraulic and pneumatic systems, and the pitot-static and gyroscopic instruments. Know how each instrument derives its reading: the altimeter, ASI, and VSI all use static pressure, while the ASI additionally uses pitot (dynamic) pressure. Gyroscopic instruments rely on rigidity and precession.
Traps to watch
A frequent trap is confusing indicated, calibrated, true, and equivalent airspeed, and forgetting position and instrument error. Another is the behaviour of the altimeter when the static source is blocked: it freezes at the altitude where the blockage occurred, while the VSI reads zero. Questions on carburettor icing test whether you know it is most likely at low power with high humidity and moderate temperatures, and that applying carburettor heat enriches the mixture. Magnetos are independent of the electrical system, so an electrical failure does not stop the engine.
Worked example
If the static port ices over in climb, the ASI behaves like an altimeter (indicated speed increases as you climb), the altimeter freezes, and the VSI reads zero. Recognising this pattern answers the classic "what fails and how" question.
Rule of thumb
Ask "which pressure does this instrument sense?" Pitot + static = ASI; static only = altimeter and VSI.