A&P Cheat Sheet 2026

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

1. What must be checked during a landing gear inspection? → Wear, leaks, and proper operation
2. What is the primary purpose of a hydraulic system's thermal relief valve? → Relieve pressure caused by thermal expansion of trapped fluid
3. Which inspection method uses high-frequency sound waves to detect flaws? → Ultrasonic testing
4. When fabricating a replacement part that requires a 90-degree bend, the term 'bend allowance' refers to: → The length of the curved portion of the metal within the bend.
5. What class of fire extinguisher is appropriate for a hydraulic fluid fire? → Class B extinguisher (for flammable liquids)
6. What is the purpose of a fuel system boost pump on a reciprocating engine aircraft? → To provide fuel pressure for starting and as a backup if the engine-driven pump fails
7. What does the term 'blade track' mean when applied to propeller inspection? → The ability of all blades to follow the same plane of rotation
8. What is the purpose of the turbocharger in an aircraft engine? → To compress intake air for better performance at altitude
9. What color is MIL-PRF-5606 mineral-based hydraulic fluid? → Red
10. In a sheet metal lap joint repair, the rivet pitch (the distance between the centers of adjacent rivets in the same row) should generally be no less than: → Three times the rivet diameter.
11. Which of the following defines the imaginary vertical plane from which all horizontal measurements of arm are taken for weight and balance purposes? → Datum
12. What material are most modern aircraft hydraulic lines made from in high-pressure sections? → 21-4N stainless steel or titanium tubing
13. What does a fuel crossfeed valve allow on a multi-engine aircraft? → It allows fuel from one wing tank to feed the engine on the opposite wing
14. When a propeller overspeed condition occurs in flight, what is the pilot's first corrective action? → Reduce throttle to decrease engine torque and allow RPM to recover
15. On a counterweight-type constant-speed propeller, what force moves the blades toward high pitch (coarse)? → Centrifugal force acting on the propeller counterweights
16. Which component controls the fuel-air mixture in a reciprocating engine? → Mixture control
17. What grade of aviation gasoline (avgas) is identified by its blue color? → 100LL (low-lead)
18. What does a fuel flow meter measure in a fuel-injected aircraft engine? → Volume or mass of fuel delivered to the engine per unit time
19. Which tool is essential for measuring torque during maintenance? → Torque wrench
20. What is the primary reason for feathering a propeller after an engine becomes inoperative in flight? → To minimize aerodynamic drag and prevent windmilling of the failed engine
21. What type of fluid is used in most modern commercial aircraft hydraulic systems? → Skydrol (phosphate ester-based)
22. How is a hydraulic actuator classified when it can produce force in both directions using hydraulic pressure? → Double-acting actuator
23. What is the correct procedure before opening a hydraulic line for maintenance? → Depressurize the system and discharge accumulators
24. Which document specifies maintenance requirements for a specific aircraft? → Aircraft Maintenance Manual
25. What is the function of the 'beta range' on a turboprop propeller control system? → To allow direct manual control of blade angle below the normal governing range
26. What is the primary purpose of a hydraulic system relief valve on an aircraft? → To limit maximum system pressure and prevent overpressure damage
27. What is the purpose of an aircraft fuel strainer (gascolator)? → Filter sediment and water from fuel before it reaches the carburetor or fuel control unit
28. Which system provides lubrication to moving engine parts? → Oil system
29. Which seal material is compatible with Skydrol hydraulic fluid? → Butyl rubber or ethylene propylene (EPDM)
30. In a pneumatic system, what component is used to remove moisture from compressed air before it enters system components? → Air/oil separator or moisture separator