AET Cheat Sheet 2026

The 30 highest-yield AET facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Which data flow topology best describes ARINC 429? → Unidirectional point-to-multipoint bus
2. What does EICAS stand for and what is its primary function? → Engine Indication and Crew Alerting System
3. Which component prevents excessive current from damaging aircraft wiring? → Circuit breaker
4. What frequency does the emergency guard channel operate on in aviation? → 121.5 MHz
5. What is the primary function of an aircraft's pitot-static system? → Flight data for speed, altitude, and climb rate
6. What word length does ARINC 429 use for each data transmission? → 32 bits
7. Which protocol architecture is used by MIL-STD-1553? → Command/response with time division multiplexing
8. What is the primary function of an audio control panel (ACP) in an aircraft? → Select and route audio between radios, navigation receivers, and crew headsets
9. What is the purpose of a transponder in an aircraft? → Transmit ID and altitude to ATC radar
10. Who is responsible for ensuring an aircraft is airworthy before flight according to FAR Part 91? → The pilot in command
11. What does the term 'bit' refer to in digital electronics? → A single binary digit (0 or 1)
12. How many Remote Terminals (RTs) can be addressed on a single MIL-STD-1553 bus? → 31
13. What does a Supplemental Type Certificate (STC) authorize? → Modification of a certificated aircraft or installation of non-original equipment
14. What document must accompany an avionics component to prove it is airworthy and approved for installation? → FAA Form 8130-3 (Airworthiness Approval Tag)
15. Why is it important to reference schematic legends when reading diagrams? → To interpret symbols and abbreviations correctly
16. What does the DME system measure? → Distance to a ground station
17. What is the fixed data transfer rate of MIL-STD-1553? → 1 Mbps
18. What is the specified characteristic impedance of a MIL-STD-1553 bus cable? → 70 ohms
19. What is required when installing avionics that affect the aircraft's operating limitations? → A Flight Manual Supplement (FMS) must be created and placed in the AFM
20. What does BIT stand for in avionics system testing? → Built-In Test
21. What is the meaning of Design Assurance Level (DAL) A in DO-178C? → Software whose failure would cause or contribute to a catastrophic failure condition
22. What does a flip-flop circuit do in digital avionics systems? → Stores a single bit of data
23. What does an Air Data Computer (ADC) primarily compute? → Airspeed, altitude, vertical speed, and Mach number from pitot-static data
24. What is the function of an aircraft's hydraulic system? → Operate flight and landing systems
25. In ARINC 664 (AFDX), what does the term 'virtual link' refer to? → A logical unidirectional communication path with guaranteed bandwidth
26. What does RTCA DO-160 specify? → Environmental testing conditions for airborne electronic equipment
27. What is the primary purpose of bonding straps in aircraft electrical systems? → To provide a low-resistance ground path and prevent static buildup
28. What tool is essential for verifying electrical continuity in avionics systems? → Multimeter
29. What is the purpose of a pitot heater in the aircraft instrument system? → Prevent ice formation in the pitot tube that would cause false airspeed readings
30. What is the primary reason for using torque specifications when tightening fasteners? → To prevent over- or under-tightening