I am dealing with this exact same thing in our Cessna 172K. We had a brand new ACK E-04 ELT put in (replaced an old 121.5 only ELT) back in June of last year.
A few weeks ago, it goes off at 6:50-ish AM while the plane is happily and safely tied down at the airport. It took over an hour before we could get someone to turn the ELT off, so we had to spend several hundred bucks on getting a new battery.
New battery goes in, and its fine for another week or so. Then, our CFI takes a student up, and the ELT triggers while they are about 2k feet in their climb. They called guard and explained they were indeed safe and the ELT is acting up, and headed back to airport. Luckily only about 15 ,minutes or so was used on this new battery. The student had to keep disarming the thing while the CFI flew them back.
our A&P pulled it, and called ACK. They had us send it for warranty repair and its supposed to be back Tuesday-ish. They fixed/replaced it under warranty but we didn't get an explanation as to what went wrong.
A friend in our EAA chapter also had his ACK E-04 act up doing the same thing a few months ago. That ELT was installed around may of last year. I wonder if a bad batch didn't go out around the first of last year or something.
RV-7 Slider -
Tail kit Completed - March 2017
Wing Kit Started - June 2017
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