Aircraft General Knowledge - Electrical, Avionics and Instruments
What you must understand
For electrical systems: DC generation (starter-generators, alternators with rectifiers), parallel operation and load sharing, busbar architecture (essential/emergency bus, bus ties), battery types and their care, circuit protection (fuses, thermal and magnetic breakers), bonding and shielding, and the significance of a ground power unit connection sequence. Understand split-bus and why essential services are isolated.
For avionics: the difference between self-contained and dependent systems; pitot-static and gyroscopic instruments; the errors of each (position error, lag, manoeuvre error, parallax). Know the pitot-static connections: pitot feeds the airspeed indicator only; static feeds ASI, altimeter and VSI. Know the colour arcs on an ASI and the meaning of V speeds. Understand attitude indication: gyroscope rigidity and precession, and how an electrically driven artificial horizon differs from a vacuum-driven one. Know the principles of radio navigation aids at the block level (VOR, DME, ILS, GNSS) and what each measures. Understand warning systems: master caution/warning philosophy, annunciators, and the difference between a warning and a caution.
Traps
Questions love blocked pitot versus blocked static. A blocked pitot with drain open behaves like an altimeter; a blocked static makes the ASI read high in climb and low in descent. Another trap is confusing a magnetic compass turning error with acceleration error.
Rule of thumb
Memorise the static source chain: ASI, altimeter, VSI. If the static line is blocked, all three misread together - that is the diagnostic clue in the question.