05/27/2026
Some pilots and aircraft owners still do not get it. Some A&P’s and IA’s still don’t get it.
What am I talking about? Replaceable D Batteries in ELT’s. Part 91.207 clearly states in Paragraph C (2) that when a battery reaches 50% of their useful life. What it means is useful shelf life after which the battery is no long holding its full charge..
Duracell is specified by most ELT manufacturers due to their performance and long shelf life. Duracell has a 10 year shelf life. That means that a battery that was labeled 2025 was manufactured in 2015 and 50% of it shelf life would be 5 years or replaced in an ELT in 2020.
Time after time I keep finding batteries like this one with this written on the outside of the ELT “Bat Exp Dec 2025” when the battery shelf life says 2025, wrong! The ELT would not activate when tested. So much for having a functioning ELT on board.