I'm getting set to install the GPS-equipped ELT-brand 406 ELT unit in my C-170B. I believe the weight of the unit is about 3 lbs, and the weight of the antenna is another 1lb.

I'm looking for ideas about where to install it in the airframe. I have extended baggage. If I install it aft of that, it has a considerable amount of arm. Forward of that, and it's one more thing in the way. Has anyone seen a nice install on a C170 or equivalent?

Also, any suggestions about locating the panel-mount switch?

Thanks,

-DP

Well, I'm turning up a few answers under other stones. Seems that there should be sufficient room beneath the extended baggage, even though I have a custom-fabricated one that is flush with the baggage floor. I'm told '50's era Cessnas even had some factory-mounted brackets under there for mounting radio power supplies, and the brackets, if still there, adapt well.

For the switch, one sensible answer is to put it someplace visible, to see it light up in the case of inadvertent activation.

I recently went through this exercise. Here's what I did: My old 121.5 ELT was mounted UNDER the Selkirk extended baggage floor. Totally inaccessible, for all practical purposes. Also, the bracket was mounted to the floor (skin) of the airplane, and it was easy to rock it back and forth....ie: It actually didn't meet the regulatory requirement for installation.

SOOooo, my mechanic fabricated a new mounting bracket, by bolting the mounting bracket to the back of one of the bulkheads in the floor of the airplane, just aft of the main baggage, with the extended baggage floor removed. To give the mount lots of stability, he then fabricated an AFT mounting bracket to mount the rear end of the ELT mounting bracket to the belly skin of the plane. This bracket was formed from aluminum angle, shrunk to conform to the belly of the airplane. This piece was then riveted to the belly skin of the airplane, and the ELT bracket was bolted to it and to the bulkhead. This provided a solid mounting base for the ELT, and it now clearly meets the mounting criteria for ELTs.

My second concern was access to the thing. I didn't want to have to remove the baggage floor to access the ELT for service or testing. So, we cut a hole in the Selkirk baggage floor that is right over top of the ELT, and fabricated a small aluminum door with cam lock fasteners to keep it closed. It's very nice, out of the way, and accessible.

Which was good, cause on the first flight, my ELT activated (while in flight, NOT on landing), and I eventually had to dig it out of the back of the plane and dismantle it from its battery to get it to shut up. This was at OSH, and I am now on a first name basis with the folks at Tyndall AFB in FL (RCC).

Anyway, we couldn't figure out any better mounting location that will keep it accessible and solidly mounted.

If you want pictures I can get some in the next couple days.

MTV

Thanks, MTV. Pictures could be helpful if you get a chance. I like the idea of the access door. Interesting to learn that that's the only way to shut it up?? Do you have the ELT-brand?

MTV,

I'm in the same boat as denali, needing to upgrade to a 406 ELT and needing a bracket. I've thought about adding a Selkirk extended baggage and using it as a mount for the ELT but from your experience I'm guessing that won't work. I am also interested in pictures of your bracket and your thoughts on your brand of ELT to make the upgrade as painless as possible.

Cheers, Bill

denalipilot wrote:Thanks, MTV. Pictures could be helpful if you get a chance. I like the idea of the access door. Interesting to learn that that's the only way to shut it up?? Do you have the ELT-brand?

It's an ACK, and the first one I got had a faulty switch. Turned itself on once, and I turned it off with the panel switch. Then it turned itself on, when I was a mile and a half from the airplane, and the panel switch wouldn't turn it off. I then had to get in the back of the plane and manually turn the switch off on the unit. Next day, the sucker turned itself on again, with the switch in the OFF position, and while sitting in the back of the plane, NOT connected to the antenna. RCC still got a good hit, including the GPS position it was transmitting, even though it wasn't connected to an antenna and it was inside the plane. Go figure. ACK sent me a new unit, and so far, no worries. They did call me to tell me that when they got the original back from me, it would activate with 1/2 G acceleration, basically a drop from a half inch or so.

I probably can't get a photo for a couple days, but I'll get it before the weekend, hopefully. Lots of stage checks right now, and I'm it.

MTV

BeeMan wrote:MTV,

I'm in the same boat as denali, needing to upgrade to a 406 ELT and needing a bracket. I've thought about adding a Selkirk extended baggage and using it as a mount for the ELT but from your experience I'm guessing that won't work. I am also interested in pictures of your bracket and your thoughts on your brand of ELT to make the upgrade as painless as possible.

Cheers, Bill

I don't think you could legally use the Selkirk as a mounting base for the ELT because it's not part of the aircraft's structure. I wouldn't use it in any case. You'd be bumping that ELT all the time if it was mounted on top of the baggage floor, and wires would be an issue as well.

Hard to describe what we did, but if you look at the belly of the plane just aft of the main baggage, ie: just behind the aft baggage removeable bulkhead, you'll see a bulkhead there... We used that bulkhead to mount the forward end of the ELT tray to, then essentially created a partial bulkhead/rib an appropriate distance aft of that to attach the aft end of the bracket to. That was made from a piece of aluminum angle, shrunk on a metal shrinker, to match the shape of the belly skin. Rivet that to the belly, and attach the ELT to both and it's solid.

Neither my mechanic nor I could figure out anywhere else to mount the thing that would meet the certification standards for mounting ELTs. And, note that some 40 % of ELT "failures" are actually cases where the ELT broke loose from it's mounting, and separated the antenna cable. In some of those cases the ELT had actually activated, but the signal wasn't strong enough to reach a satellite.

This mounting is solid as all get out. Not my idea, by the way. My mechanic came up with the idea and it's solid.

MTV

When I bought my P172D, it had a Narco ELT, which did not meet more recent TSO requirements (most notably no panel mounted switch). As soon as Artex started delivering the ME406, I got one and had it installed. It fit the Narco mount bolt pattern, although it has its own tray, and the antenna just replaced the existing one. Much easier to install than my mechanic expected. He did the stringing of the cable to the panel during the annual a month or 2 before the ELT was delivered, so that was the only major issue. I don't know if this is a TSO requirement for the 406s or is common, but one feature mine has is a piezo buzzer that goes off if the ELT activates--good for the hard landing issues!

Cary

Cary,

The audible alarm is a 406 requirement. I thought my previous installation bracket should have been fine also, until my mechanic showed me how much that installation flexed . It clearly didn't meet the required deflection standards, yet it had been installed by an IA and inspected repeatedly at annuals.....it's just that recently we've learned more about the structural integrity of ELT mounts, and more focus has been put on these. The regulation actually hasn't changed, but I'd bet a VERY high percentage of older ELT brackets can't meet the certification standard.

For me, if I'm spending that much money on a piece of equipment, I want it installed correctly. My ELT replaced an identical model, by the way, so could have used the same bracket even....just a bolt in.

Anyway, not saying yours isn't plenty stout, but next time you're at the plane, get a grip on that ELT and see if it'll flex at all in mounting. If so, it's probably not legal, but more importantly, it may not work when you really need it.

MTV

Actually already did that, out of curiosity after the new one was installed--it uses a large Velcro strap to hold the ELT to the bracket, which concerned me, but that seems pretty solid. Whoever did the original ELT installation reinforced the area with some aluminum pieces, and it also seems pretty solid to me. I suppose the only way to really know would be to wreck it, and that seems a bit extreme.

Cary

Photos of C 170 aft baggage ELT mounting:



With Door Open:



With ELT removed:



In the last photo you can see the piece of aluminum angle that's been shrunk to shape it to the belly skin, and then riveted to the belly. The front end of the ELT bracket is attached to one of the primary fuselage ribs. This provides a really solid mounting for the ELT.

The door in the Selkirk baggage floor permits access to the ELT.

MTV

MTV,
Neat installation; I'll be sure to credit you when we copy your design. Did you add the Selkirk extended baggage? Any idea how much weight it added? I would like to go there but the plane is heavy as is (1,400) and I have other things to spend money on that seem like a higher priority.
Thanks for the photos, Bill

I don't recall exactly what the Selkirk baggage weighs. Probably around ten pounds, or so, I'd guess. I can check the weight tonight. Installation isn't quite as straightforward as one would think it should be. Takes a bit of cutting and fitting. Good quality though.

I like keeping light stuff back there, and out of sight.

One thing about this installation, if you're going to do it with the Selkirk baggage, make sure you research the location first. The Selkirk baggage floor has reinforcing seams down the center and across, so the door needs to be in between those reinforcements.

MTV

MTV-

Thanks for the photos.

BeeMan-

If you are in Anchorage, you might consider going over to Ward's Aero for an example of his custom extended baggage installation. I like mine a lot, however I did just learn that there is insufficient room beneath for my ELT. Am now proceeding with a ceiling-mount location just aft of the normal baggage bulkhead. PM me if you want to check out my setup in ANC this Fri/Sat.

-DP