Instrumentation
Instrumentation questions test what a gauge actually measures, its errors, and how to interpret it. For pitot-static instruments, understand that the ASI measures dynamic pressure, the altimeter static pressure, and the VSI the rate of change of static pressure with a lag. Learn the errors: position error, instrument error, compressibility, and the density error affecting the ASI at altitude. Know the meaning of indicated, calibrated, true and equivalent airspeed.
Gyroscopic instruments: the attitude indicator and heading indicator are earth-referenced and suffer from real and apparent wander; the turn coordinator is rate-referenced. Understand rigidity and precession, and the erection system of the artificial horizon.
For navigation instruments, know how the VOR, DME, ILS and ADF displays are interpreted, and the difference between a course deviation indicator and a bearing pointer. Radio altimeter measures height above terrain, not altitude.
Engine instruments: tachometer, EGT, fuel flow and torque, and how each is sensed.
Traps: assuming the altimeter reads true altitude; forgetting that the VSI lags; and confusing the turn indicator's rate with bank angle.
Worked example: flying from high to low pressure without resetting the altimeter, the aircraft is lower than indicated. Rule of thumb: "high to low, look out below".