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fly_vans_rv7a 05-19-2017 09:25 PM

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.

bret 05-20-2017 06:46 AM

Interesting, so they use a mechanical or electronic G load-accelerometer sensor?

rv7charlie 05-20-2017 09:00 AM

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).

DHeal 05-20-2017 09:28 AM

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.

az_gila 05-20-2017 07:30 PM


Originally Posted by bret (Post 1174245)
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?

CubedRoot 05-21-2017 10:47 PM

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.

CubedRoot 07-01-2017 12:04 AM

Well, after what I thought was a corrected ELT, this happened again tonight.

From the last time it happened, ACK replaced the transmitter part of our unit since it was still under warranty, and they said they found an "issue" with it, they also told us to have our A&P rewire everything....which we did and he rewired the whole ELT system exactly to ACK's specs.

Fast forward a few weeks until tonight. I get a call from the air force asking me if my aircraft is safe. I told him unless it decided to go on a night flight by itself, it should be safe and sound on the ramp. I had to trek out to the airport and disarm the stupid thing again, and pull the control panel so it wouldn't go off.

So, since it had been triggered for about 2 hours, I have to purchase yet another stupid battery (two batteries in under 45 days now), and see why this crappy ELT keeps triggering.

I am SERIOUSLY thinking there is some flaw with these ACK units.

fly_vans_rv7a 09-17-2017 10:22 PM

Still giving me fits, my ACK-04 goes off after dusting the airplane
I thought I had solved this issue, I found a connector that might not have been fully seated and replaced the battery in the beeper and control panel units just to be safe. I've rechecked all of the harnesses and wiring. It had not gone off for months, now it's back. If I wipe down the fiberglass parts with a duster and get some static my ACK-04 ELT goes off. I can repeat this as many times as I want, I have my wife sitting it the cockpit resetting the ELT and then dust the tips and it will go off again and again.
The ELT waits 50 seconds to transmit a distress call on 406mhz, so we are NOT alerting SAR, but we are using up a VERY expensive battery.

I see that CubedRoot's 172K had the same problem and I'm hoping he found a solution.

Anyone else having a problem? If you've got a duster and you're in a dry climate give it a try.

Thanks for any help with this.

Van's RV7A

IowaRV9Dreamer 09-17-2017 11:23 PM

Ask ACK for a static suppressor. It goes behind the antenna. They game me one for free for my Beech.....I think there is a problem with sensitivity to static electricity. It took just a minute to install it. Good luck!

sf3543 09-17-2017 11:51 PM

This happened on a plane i was working on recently. After a new install, it kept going off every 20 minutes or so. In trouble shooing we isolared the audio alarm module from the system and finally everything woked fine. They sent a new module and so far it is still working, or at least not going off all the time.
Ymmv but something to consider.
God luck

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