AM AM Electrical Systems & Avionics 1 — Questions and Answers
Question 1: What is the standard voltage for most general aviation aircraft DC electrical systems?
- 12 volts
- 24 volts
- 28 volts (Correct answer)
- 48 volts
Correct answer: 28 volts
Most general aviation aircraft use a 28-volt DC electrical system, which is the FAA and MIL-SPEC standard.
Question 2: Which FAR part governs the airworthiness standards for aircraft electrical equipment?
- FAR Part 21
- FAR Part 23 (Correct answer)
- FAR Part 65
- FAR Part 91
Correct answer: FAR Part 23
FAR Part 23 establishes airworthiness standards for normal, utility, acrobatic, and commuter category airplanes, including electrical systems.
Question 3: What type of wire is required in aircraft electrical systems to prevent fire hazard in fuel tank areas?
- PVC-insulated wire
- Aluminum wire
- Teflon-insulated wire (Correct answer)
- Bare copper wire
Correct answer: Teflon-insulated wire
Teflon (PTFE)-insulated wire is required near fuel tanks because it is highly resistant to fuel, heat, and flame.
Question 4: An ammeter that reads on the discharge side of zero indicates the aircraft battery is:
- Being charged by the alternator
- Discharging to supply the bus (Correct answer)
- Fully charged and at rest
- Disconnected from the bus
Correct answer: Discharging to supply the bus
A negative (discharge) ammeter reading means the battery is supplying current to the bus because the alternator output is insufficient.
Question 5: What is the primary purpose of a current limiter in an aircraft electrical circuit?
- Regulate voltage output
- Protect wiring from overload (Correct answer)
- Increase circuit ampacity
- Balance multiple bus bars
Correct answer: Protect wiring from overload
A current limiter (fusible link) opens the circuit to protect wiring from damage caused by excessive current flow.
Question 6: When bonding aircraft components, what maximum resistance is typically allowed between bonded parts?
- 0.001 ohm
- 0.003 ohm
- 0.05 ohm (Correct answer)
- 1.0 ohm
Correct answer: 0.05 ohm
FAA Advisory Circulars specify that bonding connections should not exceed 0.003 ohm to ensure effective static discharge and EMI shielding.
AM AM Electrical Systems & Avionics 1
What is the standard voltage for most general aviation aircraft DC electrical systems?