ACS Electrical Systems & Avionics 2 — Questions and Answers
Question 1: What is the purpose of a bus bar in an aircraft electrical system?
- To convert AC power to DC power
- To distribute electrical power to multiple circuits from a common point (Correct answer)
- To regulate voltage output from the alternator
- To protect individual circuits from overcurrent
Correct answer: To distribute electrical power to multiple circuits from a common point
A bus bar serves as a common distribution point that connects multiple electrical circuits to a power source.
Question 2: When an aircraft generator fails to produce voltage, which component should be checked first?
- The voltage regulator
- The generator brushes and slip rings (Correct answer)
- The circuit breaker panel
- The battery master switch
Correct answer: The generator brushes and slip rings
Worn or dirty brushes are a common cause of generator output failure and should be inspected first.
Question 3: What does the term 'floating ground' indicate in aircraft wiring troubleshooting?
- A ground wire with excessive resistance or an open circuit (Correct answer)
- A grounded circuit with proper continuity
- A wire that is not connected to any circuit
- A shielded coaxial cable ground
Correct answer: A ground wire with excessive resistance or an open circuit
A floating ground refers to a ground connection that has high resistance or is completely open, preventing proper circuit completion.
Question 4: What type of wire insulation is required in areas of an aircraft exposed to fuel or hydraulic fluid?
- PVC insulated wire
- Cloth-braided wire
- Fluid-resistant insulated wire such as PTFE or nylon-jacketed (Correct answer)
- Standard copper wire with no insulation
Correct answer: Fluid-resistant insulated wire such as PTFE or nylon-jacketed
Wiring in areas exposed to fluids must use fluid-resistant insulation like PTFE (Teflon) or nylon jacketing to prevent degradation.
Question 5: Which instrument uses a Wheatstone bridge circuit to measure fuel quantity?
- The capacitance-type fuel quantity system (Correct answer)
- The float-type fuel quantity system
- The resistor-type fuel quantity system
- The pressure-differential fuel system
Correct answer: The capacitance-type fuel quantity system
Capacitance-type fuel quantity systems use a Wheatstone bridge to compare capacitance values and determine fuel quantity accurately.
Question 6: What is the correct method for splicing aircraft wiring when a connector is not available?
- Twist the wires together and wrap with electrical tape
- Use a solderless crimp splice with approved heat-shrink tubing (Correct answer)
- Solder the splice without any additional protection
- Use a wire nut connector
Correct answer: Use a solderless crimp splice with approved heat-shrink tubing
FAA-approved crimped splices with heat-shrink tubing are the correct method; wire nuts and tape are not approved for aircraft.
Question 7: A pilot reports intermittent compass deviation when the landing gear is cycled. What is the most likely cause?
- Excessive ferrous metal near the compass
- A chafed wire in the landing gear circuit creating electromagnetic interference (Correct answer)
- A faulty compass compensation card
- Low battery voltage during gear retraction
Correct answer: A chafed wire in the landing gear circuit creating electromagnetic interference
A chafed wire can create intermittent shorts that generate magnetic fields near the compass, causing temporary deviation.
ACS Electrical Systems & Avionics 2
What is the purpose of a bus bar in an aircraft electrical system?