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. When calibrating a pressure transducer used in an aircraft fuel quantity system, which test equipment is most appropriate? → Dead-weight tester or precision pneumatic pressure calibrator
2. What is the purpose of a Continued Airworthiness document issued with an STC? → To provide the maintenance instructions necessary to keep the STC'd modification airworthy
3. What is the significance of documentation in Avionics Systems? → It provides a record for accountability, quality assurance, and legal compliance
4. Which regulatory body oversees the airworthiness standards for transport-category aircraft avionics installations? → FAA Aircraft Certification Service
5. When performing a continuity check on an aircraft wiring harness, the technician should FIRST: → Disconnect power and verify the circuit is de-energized before testing
6. When an avionics technician discovers a discrepancy during an inspection that cannot be corrected before flight, what document must be used to record it? → Discrepancy log in the aircraft maintenance record
7. When analyzing data from an avionics test set, which of the following is a crucial aspect to verify? → The accuracy of the measurements and comparison with expected values
8. Which test instrument captures and simultaneously displays multiple digital signal states to aid in troubleshooting microprocessor-based avionics? → Logic analyzer
9. An Aircraft Service Difficulty Report (SDR) is required when? → When a failure, malfunction, or defect that could endanger safe operation is discovered
10. What is the nominal voltage of a standard 14-volt aircraft electrical system when measured at the bus with the alternator online? → 13.8–14.5 volts
11. What is the best practice for communicating maintenance findings to other team members? → Provide clear, concise, and understandable information
12. When troubleshooting an aircraft electrical system and the ammeter shows a discharge indication with the engine running, what is the most likely cause? → The alternator is not producing output or is off-line
13. An ARINC 664 (AFDX) network in a modern aircraft serves as a replacement for which older avionics data bus architecture? → ARINC 429 point-to-point buses
14. What is the primary purpose of performing a routine inspection on an aircraft's electronic systems? → To ensure the system components are functioning correctly and safely
15. In an aircraft's avionic system, what does an oscilloscope primarily measure? → Voltage and current over time
16. An ELT (Emergency Locator Transmitter) certified to TSO-C126 transmits on which frequency? → 406 MHz and 121.5 MHz
17. Which type of data transmission sends bits one at a time sequentially over a single channel? → Serial transmission
18. Which oscilloscope control is adjusted to stabilize a repetitive waveform so it appears stationary on the screen? → Trigger level and source
19. When an avionics technician replaces a component in a pitot-static system, which regulatory requirement must be satisfied before return to service? → An altimeter system and altitude reporting equipment test per FAR 91.411/91.413
20. What is the primary function of a capacitor in an electronic circuit? → To store electrical energy temporarily
21. In a twin-engine aircraft with two generators, what component automatically connects both generators to share the electrical load? → Bus tie relay (BTR) or bus tie breaker
22. When an autopilot system's pitch channel fails to hold altitude and continually pitches nose-up, the most logical first diagnostic step is to check: → The pitch attitude signal from the AHRS and the elevator servo feedback signal
23. Which type of fire extinguisher is approved for use on an avionics bench fire involving energized electrical equipment? → Class C dry chemical or CO2 extinguisher
24. The ARINC 429 data bus used in commercial aviation is best described as a: → Single-transmitter, multiple-receiver unidirectional bus
25. Standard aircraft AC bus voltage and frequency for most commercial transport aircraft is: → 115V AC at 400 Hz
26. An aircraft's Master Minimum Equipment List (MMEL) is approved by the FAA and forms the basis for an operator's: → Minimum Equipment List (MEL)
27. Why is it important to document all maintenance activities performed on aircraft electronic systems? → To ensure compliance with regulatory requirements and provide a history of work performed
28. Which type of aircraft battery is most commonly used in modern general aviation aircraft due to its maintenance advantages? → Sealed absorbed glass mat (AGM) lead-acid
29. What is the most important foundational concept in Navigation Equipment? → Understanding core principles and their practical application in Navigation Equipment
30. What does SELCAL stand for in aircraft communication systems? → Selective Calling System