AET Digital Electronics 2 — Questions and Answers
Question 1: What is the primary characteristic of the ARINC 429 data bus used in commercial aviation?
- Bidirectional multi-master bus
- Unidirectional single transmitter to multiple receivers (Correct answer)
- Full duplex Ethernet
- Half-duplex with collision detection
Correct answer: Unidirectional single transmitter to multiple receivers
ARINC 429 is a unidirectional bus with one transmitter and up to 20 receivers, widely used in commercial transport aircraft.
Question 2: What word length does ARINC 429 use for each data transmission?
- 8 bits
- 16 bits
- 32 bits (Correct answer)
- 64 bits
Correct answer: 32 bits
Each ARINC 429 word is 32 bits long, containing a label, source/destination identifier, data, sign/status matrix bits, and a parity bit.
Question 3: What does a flip-flop circuit do in digital avionics systems?
- Converts analog to digital
- Stores a single bit of data (Correct answer)
- Amplifies digital signals
- Generates clock pulses
Correct answer: Stores a single bit of data
A flip-flop is a bistable multivibrator that stores one bit of digital information, maintaining its output state until triggered to change.
Question 4: In avionics software, what does DO-178C define?
- Hardware qualification requirements
- Software development and assurance levels for airborne systems (Correct answer)
- EMI testing procedures
- ARINC data word formats
Correct answer: Software development and assurance levels for airborne systems
RTCA DO-178C defines the software development and verification processes required for airborne software to meet FAA certification levels (DAL A–E).
Question 5: What is the function of a data concentrator unit (DCU) in a modern avionics suite?
- Generate navigation data
- Collect, process, and route data from multiple avionics sensors to display systems (Correct answer)
- Provide electrical power conversion
- Control autopilot servos
Correct answer: Collect, process, and route data from multiple avionics sensors to display systems
A DCU aggregates data from multiple avionics buses and sensors, formats it, and distributes it to cockpit display systems and other LRUs.
Question 6: What does the term 'LRU' stand for in avionics maintenance?
- Low Range Unit
- Line Replaceable Unit (Correct answer)
- Local Radio Unit
- Load Regulation Unit
Correct answer: Line Replaceable Unit
LRU (Line Replaceable Unit) is an avionics component designed to be quickly removed and replaced at the flight line without depot-level maintenance.
AET Digital Electronics 2
What is the primary characteristic of the ARINC 429 data bus used in commercial aviation?