CAT Avionics and Electrical Systems 2 — Questions and Answers
Question 1: What is the primary function of an aircraft Auxiliary Power Unit (APU)?
- Provide supplemental engine thrust during takeoff
- Supply electrical power and bleed air when main engines are not running (Correct answer)
- Control hydraulic system pressure on the ground
- Power the landing gear extension system
Correct answer: Supply electrical power and bleed air when main engines are not running
The APU provides electrical power and pneumatic bleed air for engine starting and environmental control when main engines are shut down.
Question 2: In avionics maintenance, what does the acronym BITE stand for?
- Built-In Test Equipment (Correct answer)
- Basic Instrument Testing Environment
- Binary Interface Transfer Equipment
- Built-In Troubleshooting Engine
Correct answer: Built-In Test Equipment
BITE (Built-In Test Equipment) refers to self-diagnostic hardware and software integrated into avionics units to detect and report system faults.
Question 3: Which wire insulation material is most commonly used in aircraft applications for its high-temperature resistance and low flammability?
- PVC (Polyvinyl Chloride)
- Rubber
- PTFE (Polytetrafluoroethylene/Teflon) (Correct answer)
- Nylon
Correct answer: PTFE (Polytetrafluoroethylene/Teflon)
PTFE (Teflon) is preferred in aircraft wiring due to its excellent temperature resistance, chemical inertness, and low flammability under aerospace conditions.
Question 4: What is the function of a Bus Tie Breaker (BTB) in an aircraft AC electrical system?
- Connect individual loads directly to generator output
- Interconnect multiple AC buses or isolate a faulted bus from the network (Correct answer)
- Convert three-phase AC to single-phase AC
- Regulate output voltage from the Integrated Drive Generator
Correct answer: Interconnect multiple AC buses or isolate a faulted bus from the network
Bus Tie Breakers allow power sharing between generators by connecting buses together or isolate a faulted bus to protect the remaining healthy electrical network.
Question 5: Which avionics system specifically warns flight crews of potential Controlled Flight Into Terrain (CFIT)?
- TCAS (Traffic Collision Avoidance System)
- ACARS (Aircraft Communications Addressing and Reporting System)
- TAWS/GPWS (Terrain Awareness and Warning System / Ground Proximity Warning System) (Correct answer)
- SELCAL (Selective Calling System)
Correct answer: TAWS/GPWS (Terrain Awareness and Warning System / Ground Proximity Warning System)
TAWS/GPWS monitors aircraft altitude, terrain proximity, and flight path geometry to alert crews before potential ground impact.
Question 6: What does the military specification MIL-W-22759 govern in aerospace applications?
- Military aviation hydraulic fluid lines
- Flexible hookup wire for aerospace and military use (Correct answer)
- Structural fastener installation procedures
- Aircraft hydraulic tubing dimensions
Correct answer: Flexible hookup wire for aerospace and military use
MIL-W-22759 specifies flexible hookup wire for aerospace use, typically with PTFE or ETFE insulation, rated for high temperature and harsh environments.
Question 7: What does Fly-by-Wire (FBW) technology replace in conventional aircraft flight control systems?
- Hydraulic fluid with compressed air actuators
- Mechanical cables and linkages with electronic signal transmission to actuators (Correct answer)
- Analog cockpit instruments with digital displays
- Autopilot systems with manual control inputs
Correct answer: Mechanical cables and linkages with electronic signal transmission to actuators
Fly-by-Wire replaces traditional mechanical push-pull rods and cables with electronic control signals transmitted by wire to electrically-commanded hydraulic or electric actuators.
CAT Avionics and Electrical Systems 2
What is the primary function of an aircraft Auxiliary Power Unit (APU)?