FAA Aviation Mechanic Airframe (AMA)Airframe InspectionEasy
A pilot asks a technician how often the ATC transponder system must be tested and inspected under 14 CFR to remain legal for IFR and controlled airspace operations. What is the required interval?
- AEvery 24 calendar months
- BEvery 12 calendar months
- CEvery 100 hours of operation
- DOnly at the time of initial certification
Show answer & explanationAnswer & explanation
Correct answer: A. Every 24 calendar months
14 CFR 91.413 requires that the ATC transponder system be tested and inspected every 24 calendar months by an appropriately certificated repair station or technician using approved test equipment.
Why the other options are wrong
- B. 12 months is the annual inspection interval, not the transponder test interval.
- C. 100 hours applies to inspections on aircraft used for hire, not transponder testing.
- D. The transponder must be retested periodically, not just once.
Transponder Test (91.413)
A required periodic functional and altitude reporting test of the ATC transponder system performed every 24 calendar months per 14 CFR 91.413.
- 24-calendar-month interval
- Required for operation in controlled airspace requiring transponder use
- Must be performed per 14 CFR Part 43 Appendix F test procedures
Memory trick: 'Transponder Talks every Two years' — 24 months.