FAA Aviation Mechanic Airframe (AMA)Airframe Electrical and InstrumentsMedium
A technician is performing a static system leak check on an unpressurized single-engine airplane in accordance with 14 CFR Part 43, Appendix E. After applying suction to simulate a climb to altitude and sealing the system, the altimeter should not indicate a loss of more than what value in one minute for the system to be considered airtight?
- A50 feet
- B20 feet
- C250 feet
- D100 feet
Show answer & explanationAnswer & explanation
Correct answer: D. 100 feet
Per 14 CFR Part 43, Appendix E, the static pressure system of an unpressurized aircraft is considered acceptable if the altimeter does not lose more than 100 feet of indicated altitude in one minute after the test altitude is stabilized, confirming the system holds pressure with no significant leaks.
Why the other options are wrong
- A. 50 feet is not the standard tolerance specified in Appendix E.
- B. 20 feet is far stricter than the actual regulatory tolerance.
- C. 250 feet would allow a leak far in excess of the regulatory limit.
Static System Leak Check
A test required under 14 CFR Part 43 Appendix E to verify the airtightness of the pitot-static system by monitoring altimeter indication decay after applying vacuum.
- Applies to altimeter/static system tests every 24 calendar months
- Unpressurized aircraft: max 100 ft loss in 1 minute
- Test is part of the required altimeter and static system inspection
Memory trick: 100 feet, 1 minute — the century mark for a tight static system.