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Old 05-19-2017, 08:25 PM
fly_vans_rv7a fly_vans_rv7a is offline
Join Date: Mar 2006
Location: Sedona, Arizona
Posts: 12
Default ACK E-04 ELT has triggered 3 times while stationary.

We finished our 3rd RV build this last November and in the past 5 months our ACK ELT-04 406mhz has gone off 3 times in our hangar while stationary.
I've received calls from SAR and I've called ACK technologies to find an answer. They said they haven't received complaints of this nature and to send it in if I want them to look at it. I've rechecked the installation, batteries and static suppressor near the antenna. I've installed ELT's in the past 4 airplanes we've built, this is the first with a GPS input.

Tonight I was dusting off our airplane with a "California duster" dusting mop and my ELT went off AGAIN! I noticed static build up while dusting.

Has this happened to anyone else?
Thanks for any input on this.
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Old 05-20-2017, 05:46 AM
bret's Avatar
bret bret is offline
Join Date: Feb 2010
Location: Gardnerville Nv.
Posts: 2,488

Interesting, so they use a mechanical or electronic G load-accelerometer sensor?
7A Slider, EFII Angle 360, CS, SJ.
2017 gladly supported
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Old 05-20-2017, 08:00 AM
rv7charlie rv7charlie is offline
Join Date: May 2006
Location: Pocahontas MS
Posts: 1,901

There was a similar issue with one brand of 121.5 ELTs a number of years ago, where RF & other stray energy would trigger them. Couldn't find any internet references, but IIRC, it started after the FAA started requiring remote indicator/control panels visible to the pilot (long runs of wire & an extra circuit board was an entry point into the ELT).
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Old 05-20-2017, 08:28 AM
DHeal DHeal is online now
Join Date: Sep 2006
Location: Windsor, California
Posts: 551

As a data point, I use a California Duster to dust the surfaces of my RV-12 -- no ACK ELT-04 issues in past three+ years.
David Heal - Windsor, CA (near Santa Rosa)
EAA #23982 - EAA Technical Counselor and Flight Advisor; CFI - A&I
RV-12 E-LSA #120496 (SV w/ AP and ADS-B) - N124DH flying since March 2014 - 510+ hours (as of June 2017)!
VAF donation through June 2018.
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Old 05-20-2017, 06:30 PM
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az_gila az_gila is offline
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 8,433

Originally Posted by bret View Post
Interesting, so they use a mechanical or electronic G load-accelerometer sensor?
That's the sensor, but it can also be triggered by the remote panel switch.

Perhaps an intermittent short in the cable to the remote sensor?
Gil Alexander
EAA Technical Counselor, Airframe Mechanic
RV-6A N61GX - finally flying
Grumman Tiger N12GA - flying
La Cholla Airpark (57AZ) Tucson AZ
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Old 05-21-2017, 09:47 PM
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CubedRoot CubedRoot is offline
Join Date: Sep 2013
Location: Ooltewah, TN.
Posts: 345

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.
Lynn Dixon
RV-7 Slider -
Tail kit Completed - March 2017
Wing Kit on its way!
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