Erroneous ELT Activation

[JJ Campbell]

Earlier this year I was getting frequent inappropriate ELT activations. It was suggested by the manufacturer that these were caused by some coiled up wires lying on top of the communications antenna. So, based on that, the coil of wire you see in the lower left-hand corner of the attached photo were repositioned to their current location in early June.

It appeared that this solved the problem since I had 30 flights and nearly 100 hours w/o and activation. Sadly, on 9/27 I had two activations. One on final to SFQ and another after returning home to JYO after the plane was turned off, tied down and while debugging the wings. Luckily, the SARs folks got me on the phone before I left the airport.

I'm wondering if there is something I could wrap all the wires with to shield them?

Any suggestions will be much appreciated!

[3Dreaming]

I don't have an answer on the wires, but I know of others who have had the same ELT activate without cause.

Now that being said, how solid is the structure that it is mounted to? It looks like a fiberglass box. If that is the case it does not meet the TSO for mounting, and it is possible that could be the source for it going off.

[JJ Campbell]

Now that being said, how solid is the structure that it is mounted to? It looks like a fiberglass box. If that is the case it does not meet the TSO for mounting, and it is possible that could be the source for it going off.

I'll have to look at it next time I'm at the plane. How solid is it supposed to be per the TSO?
*Edit*
Now that I think of it - that has to be the baggage compartment that has a door on the outside of the plane on the fuselage. So, definitely fiberglass.

[3Dreaming]

This is what the ELT manual says, no more than 1/10 inch deflection on the most flexible direction with 100 pounds of force. Here is a link to their page which has a link to the manual. Mounting is in section 2.

https://www.ackavionics.com/e-04-technical-information/

[3Dreaming]

There is a post in the attached thread from the CT Flier forum that talks about spontaneous activation of a ACK ELT, and some trouble shooting items.
http://ctflier.com/topic/6599-bad-elt/? ... ment-91064

[JJ Campbell]

There is a post in the attached thread from the CT Flier forum that talks about spontaneous activation of a ACK ELT, and some trouble shooting items.
http://ctflier.com/topic/6599-bad-elt/? ... ment-91064

Thanks good info. I see the same ACK MO. Bad job installing, plane got wet etc. Zero, acknowledgement by ACK that their product is just too damned finicky. Customer support from their main guy Mike Akatiff is awful. He is surly, rude and not at all helpful. His last suggestion to me was pull it all out and reinstall following the manufacturers procedures. Which I'll have done during my next conditional. However, I will NEVER contact ACK for "Help" again. If the problem is not resolved after my conditional or if the unwarranted activations become more than just occasionally, I'll replace the 18 month old unit with and Artex 345.

My advice to anyone considering a new ELT is to steer clear of ACK!

[JimParker256]

JJ, the picture you posted appears to be an ELT installed onto a plastic / fiberglass tank of some kind (fuel?). If my visual interpretation is correct, that installation would NOT comply with the requirements documented in the ACK installation manual. If an ELT were to be installed on a flexible plastic surface like that, I would absolutely expect to have false activations during "firm" landings, as well as during turbulence in-flight. And if/when it activates, you should immediately hear the ELT alarm sounding, and see the ELT "ON" light flashing on the ELT switch itself.

For your reference, Section 2 of the installation manual kicks off with the statement: "Several problems associated with previous TSO C-91, and C-91a ELT installations, is the result of poorly chosen mounting locations." False activations of ELTs has been a significant issue in the past, and all the ELT manufacturers were required by the FAA to beef up their installation manuals to reduce those false activations.

You can see the result of that a couple of paragraphs farther down that section, where it states: "The ELT shall be mounted to primary load-carrying structures such as trusses, bulkheads, longerons, spars, or floor beams. (not aircraft skin) The mounts shall have a maximum static local deflection no greater than 2.5mm (0.1 inch) when a force of 450 newton's (100 lbs.) is applied to the mount in the most flexible direction. Deflection measurements shall be made with reference to another part of the airframe not less than 0.3 meter (1 foot) nor more than 1.0 meter (3 feet) from the mounting location."

Note the use of "shall" in that statement about installing the mount to a primary load-carrying structure. That signifies (in FAA language) that this is a mandatory (not optional) requirement for airworthiness. I'm not trying to defend the attitude (or tone) of the ACK person you spoke with, since I wasn't on the call. But my recommendation would be the same as you got from him: The ELT needs to be removed and reinstalled IAW the ACK installation manual.

I'm curious whether an A&P signed off on the current installation, and whether it's been through an annual inspection / condition inspection by a different A&P/IA since the original installation?

[JJ Campbell]

JJ, the picture you posted appears to be an ELT installed onto a plastic / fiberglass tank of some kind (fuel?). If my visual interpretation is correct, that installation would NOT comply with the requirements documented in the ACK installation manual. If an ELT were to be installed on a flexible plastic surface like that, I would absolutely expect to have false activations during "firm" landings, as well as during turbulence in-flight. And if/when it activates, you should immediately hear the ELT alarm sounding, and see the ELT "ON" light flashing on the ELT switch itself.

For your reference, Section 2 of the installation manual kicks off with the statement: "Several problems associated with previous TSO C-91, and C-91a ELT installations, is the result of poorly chosen mounting locations." False activations of ELTs has been a significant issue in the past, and all the ELT manufacturers were required by the FAA to beef up their installation manuals to reduce those false activations.

You can see the result of that a couple of paragraphs farther down that section, where it states: "The ELT shall be mounted to primary load-carrying structures such as trusses, bulkheads, longerons, spars, or floor beams. (not aircraft skin) The mounts shall have a maximum static local deflection no greater than 2.5mm (0.1 inch) when a force of 450 newton's (100 lbs.) is applied to the mount in the most flexible direction. Deflection measurements shall be made with reference to another part of the airframe not less than 0.3 meter (1 foot) nor more than 1.0 meter (3 feet) from the mounting location."

Note the use of "shall" in that statement about installing the mount to a primary load-carrying structure. That signifies (in FAA language) that this is a mandatory (not optional) requirement for airworthiness. I'm not trying to defend the attitude (or tone) of the ACK person you spoke with, since I wasn't on the call. But my recommendation would be the same as you got from him: The ELT needs to be removed and reinstalled IAW the ACK installation manual.

I'm curious whether an A&P signed off on the current installation, and whether it's been through an annual inspection / condition inspection by a different A&P/IA since the original installation?

The ELT is mounted on top of the outside accessible baggage compartment. It is very sturdy and has zero flexibility. None of the many activations has occurred during hard landings or in turbulence. Every activation has been on base or final or after the plane is on the ground with everything turned off. Yes, the initial installation was done by and A&P and the plane was given a conditional a year later by another A&P at a different shop 70 nm away from the original installer. The coil of wire that was lying on top of the com antenna was relocated during the conditional. The quote I used from the ACK tech was one of his politer ones...