FAA Sport Pilot Airplane (SPA)RegulationsHard
A mechanic performing an inspection on an emergency locator transmitter (ELT) needs to determine when the battery must be replaced or recharged. According to 14 CFR 91.207, when must this occur?
- AOnly when the ELT fails a self-test check
- BAfter 1 cumulative hour of use, or when 50% of the battery's useful life has expired, whichever occurs first
- CEvery 24 calendar months regardless of use
- DAfter 100 flight hours since the last replacement
Show answer & explanationAnswer & explanation
Correct answer: B. After 1 cumulative hour of use, or when 50% of the battery's useful life has expired, whichever occurs first
14 CFR 91.207(c) requires ELT batteries to be replaced (or recharged if rechargeable) after 1 cumulative hour of use, or when 50 percent of the battery's useful life (or, for rechargeable batteries, 50 percent of useful life of charge) has expired, whichever occurs first.
Why the other options are wrong
- A. Self-test failure would trigger replacement but is not the only scheduled criterion.
- C. 24 months is unrelated; it's tied to usage and battery life, not a flat calendar interval.
- D. Flight hours since replacement isn't the regulatory metric; it's ELT operating time and battery life percentage.
ELT Battery Replacement Rule
ELT batteries must be replaced/recharged after 1 cumulative hour of use or 50% of useful life, whichever comes first (14 CFR 91.207(c)).
- Applies to both usage time and calendar-based battery life
- Date of replacement must be marked on the battery/ELT
- Applies to most airplanes carrying an ELT under 91.207
Memory trick: 'One hour used or half its life—whichever hits first, swap the battery.'