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Transponder test and inspection interval

Aviation Mechanic Airframe (AMA) practice question 9 of 26 on Communications, Light Signals, and Runway Lighting Systems. ACS element AM.II.I.K21 · difficulty: recall. Want to answer it in a timed quiz? Use the Aviation Mechanic Airframe (AMA) practice mode.

Question bank updated 2026-09-22

QUESTIONUnder 14 CFR part 91, section 91.413, how often must the transponder on an aircraft flown into controlled airspace be inspected and tested?

  1. AEvery 12 calendar months
  2. BEvery 24 calendar months
  3. CEvery 30 days when flown IFR
Show the answer and explanation

Correct answer: B. Every 24 calendar months

  • A — incorrect Twelve months is the ELT inspection interval; the transponder interval is twice that long.
  • B — correct Section 91.413 requires the inspection and test in accordance with 14 CFR part 43, Appendix F every 24 calendar months.
  • C — incorrect No 30-day transponder test exists; the requirement is stated in calendar months and is not tied to flight rules.

BACKGROUND

A radar beacon transponder gives air traffic control positive identification and location of an aircraft, and with an altitude encoder it also supplies pressure altitude for display next to the target. Title 14 of the Code of Federal Regulations part 91, section 91.413 states that all transponders on aircraft flown into controlled airspace must be inspected and tested in accordance with 14 CFR part 43, Appendix F every 24 calendar months. Installation or maintenance that may introduce a transponder error is also cause for an inspection and test under Appendix F. Only an appropriately rated repair station, the aircraft manufacturer if it installed the transponder, and holders of a continuous airworthiness program may conduct the procedures.

STUDY TIP

Memorize the pairing of section 91.413 with part 43 Appendix F and the 24-calendar-month interval, and note that maintenance which could introduce error also triggers a retest.

KEY POINTS

  • Transponders require inspection and test every 24 calendar months.
  • The test procedures are in 14 CFR part 43, Appendix F.
  • Only approved facilities, such as a rated repair station, may perform the test.

SOURCES

  • 14 CFR 91.413
  • FAA-H-8083-31B ch11 "Transponder Tests & Inspections"
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SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-31B Aviation Maintenance Technician Handbook – Airframe, and 14 CFR part 43. Regulations and handbooks are revised; confirm details against the current edition.