406MHz ELT Installation Options?

[PeteMc]

Just did a search and was surprised that both "406" and "ELT" brought up 0 results...

I'm finally going to break down and install a 406MHz ELT as we're planning on heading back to Canada for some trips.  Granted there are not a lot of choices, but does anyone have any great or horrific stories on any particular brand/model? 

And I know that the typical antenna installation is on the outside, but I'm discussing with my avionics shop the options.  My reservation against an exterior antenna is that if I land belly down and am sitting in the shade waiting for S&R, it doesn't matter.  But if I have no option but which trees to I go into in the PNW or Canada, then the odds are extremely high the antenna is going to get ripped off.  So what's the point of even having the ELT. 

I'd love for there to be a low profile or skin attached antenna which would survive numerous tree branch hits, but I haven't seen one yet, so I'm leaning towards mounting the antenna internally.  (I have not check to see if I legally even have this option or if the manufacturer requires external...)  I figure if something happens I'll engage the ELT at altitude and it should transmit with plenty of power to reach the satellite.  Then between the ELT and ADS-B, S&R will have a good idea of the vicinity I went down.  Once in the area, even in a valley in the trees and upside down, there should still be enough power for them to track the ELT.  With a destroyed external antenna a 20 sq mile dense forest is going to make it difficult to find me.  Even if it's a 5 sq mile block of trees, there's still a chance that they'd miss where I went through the tops of the trees.

Thoughts?  Learn from your experience stories?

 

[The Other Red Baron]

I'm 99% sure our ELT antenna is externally mounted right near the tail topside. I don't know how much thought was put into where it was placed because that was before my time, but that is where it sits.

[PeteMc]

4 minutes ago, The Other Red Baron said:

externally mounted right near the tail topside

In doing more reading it looks like it may be a requirement to mount it on the exterior in a metal aircraft.  Fabric have a choice, but since it takes a metal ground plane, most probably mount it inside with a hunk of metal attached to the frame.

So looking at impact ratings might be my only option on the antenna. 

 

[Fly Boomer]

1 hour ago, PeteMc said:

Just did a search and was surprised that both "406" and "ELT" brought up 0 results...

Sometimes you will have better luck using your browser's search function like this:

site:mooneyspace.com 406 elt

With that search, I get dozens if not hundreds of hits.

Also, I think I read a topic on this forum about antenna mounting inside the fin just forward of the vertical stabilizer.

[dzeleski]

I had an Artex ELT installed with a whip antenna that is mounted right around where the rib of the vertical stab starts to bulge out. There is also a switch and light installed on the panel for it.

Cost was $916 for the ELT, $1000 to remove the old one and install the old one (6 hours of labor charged).

I have had no issues with it so far.

[Fly Boomer]

21 minutes ago, dzeleski said:

mounted right around where the rib of the vertical stab starts to bulge out

OP was "leaning towards mounting the antenna internally."

[dzeleski]

22 minutes ago, Fly Boomer said:

OP was "leaning towards mounting the antenna internally."

I understand im just providing some context for them. There is this:

But to me since the kit is not available a good amount of time is involved to fabricate the antenna into the dorsal. It also oddly goes against artexes manual stating that the antenna needs to be vertical.

The only non whip style antenna that I am aware of from my research is this: https://www.aircraftspruce.com/pages/av/antenna_elt/114-042-600.p

[KSMooniac]

The ARTEX 110-773 antenna will bend under the fiberglass dorsal fin and Mooney has an SB to support this installation.  I'm wrapping mine up this weekend.  My original was outside, just aft of the baggage door, and I wanted to get it out of the airstream for drag reduction.  It is a lot of effort, but worth it for me.  I bought a Artex 345 kit with that antenna and a slimline switch that dropped-in to my old Ameriking switch location.  The wiring is of course different.

A belt-and-suspenders approach is best if you're concerned about the airplane's ELT working, so you can always carry a separate PLB and activate it as soon as you know you're landing off-airport.  Then it doesn't matter if your airplane antenna gets damaged.

[GeeBee]

I used the Kannad Integra. I like this unit because it has an internal GPS and internal antenna. So if the external is damaged it still transmits. You can also remove the unit from the wreckage and use the internal antenna. I used a rod antenna near the tail, and notice zero difference in TAS but you can use a blade if you are a speed demon. There is one good thing about an antenna outside the tail enclosure and that is you know if it survived the crash or not. 

 

[Mooneymite]

I shouldn't hijack this thread, but with cell phones, ADS-B and such enhancements, in most of the country, perhaps ELTs are becoming unnecessary....at least for the older ELTs.  I have an acquaintance with the CAP who tells me very few "finds" are solely due to ELTs.

Getting rid of an FAR, of course, is a totally different issue.  

Edited July 14, 2022 by Mooneymite

[PeteMc]

8 minutes ago, Mooneymite said:

I shouldn't hijack this thread, but with cell phones, ADS-B and such enhancements, in most of the country, perhaps ELTs are becoming unnecessary....

Maybe in some parts of the country, but I can tell you not in the NW or to the south as you follow the Rockies.  Where we usually hike the is NO cellular service for miles and miles.  Even closer to the lake there a LOT of dead spots.  And ADS-B can go away below 5000 ft pending where you are and what mountain is between you and the ground based tower.  And even if it's more like 3000 ft that you loose ADS-B, you can travel pretty far in a Mooney at Best Glide speed. 

406MHz ELT will be spitting out your location at least until you rip off the antenna, so they're going to have a relatively good idea where you are.  But even then if it's the side of a mountain, etc. where you first go into the trees and where you finally come to rest could be a fair distance.  Which was my original reason for the internal antenna. 

I've got the SB for modifying the antenna and I'm intrigued with the Kannad Integra @GeeBee just mentioned.  (Blade antenna is an option, but not at the prices I've seen...)

 

[EricJ]

ELT antennas are carefully engineered to do their job, which includes surviving crashes as much as possible.  Bending the antenna and putting it behind a cover will not improve its performance, and the cover will attenuate the signal somewhat, which is not desirable for emergency equipment.

Mine is mounted dorsally, in the same location where the old 121.5 ELT antenna was.    There's a VHF comm antenna in front of it that will clear some branches before they get to the ELT, which is still pretty flexible.   I feel better with it there than bent underneath a cover.

It's all tradeoffs, and nobody can predict what will happen in a crash, but it seems like sometimes people don't think crashworthiness was considered in the design of an antenna for emergency equipment, which I don't think is the case.

[PeteMc]

43 minutes ago, EricJ said:

and the cover will attenuate the signal somewhat

Yep, understand the transmission issues as I said in my original post.  It's a trade-off and I think one that might be better to have slightly (TBD) dampened radiation vs snapping off the antenna. 

 

[kortopates]

i have one up on the skin by dorsal fin install since only the Airtex (?) ELT that mooney sold the service kit for was actually approved to install in the fin. All the others , including model used by Mooney require the antenna to be installed vertically. Talking to ACK, that was all that they tested with. Experimental installs can do what ever they want and do.

I went with ACK E-04 with whip antenna, but wanted redundancy so always cary a 406 PLB. The ACK gets WASS GPS position data from panel GTN. i think this is superior because it guarantees last know position being transmitted and eliminates the need for ELT to get a GPS position at the crash site.

More recently I added a Garmin InReach because it allows me to communicate my emergency medical needs to SAR personnel as well as have a backup beacon.

Today i would probably skip the ACR PLB and just add the Garmin InReach, but it has a monthly messaging subscription cost.


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[Ragsf15e]

23 hours ago, PeteMc said:

Just did a search and was surprised that both "406" and "ELT" brought up 0 results...

I'm finally going to break down and install a 406MHz ELT as we're planning on heading back to Canada for some trips.  Granted there are not a lot of choices, but does anyone have any great or horrific stories on any particular brand/model? 

And I know that the typical antenna installation is on the outside, but I'm discussing with my avionics shop the options.  My reservation against an exterior antenna is that if I land belly down and am sitting in the shade waiting for S&R, it doesn't matter.  But if I have no option but which trees to I go into in the PNW or Canada, then the odds are extremely high the antenna is going to get ripped off.  So what's the point of even having the ELT. 

I'd love for there to be a low profile or skin attached antenna which would survive numerous tree branch hits, but I haven't seen one yet, so I'm leaning towards mounting the antenna internally.  (I have not check to see if I legally even have this option or if the manufacturer requires external...)  I figure if something happens I'll engage the ELT at altitude and it should transmit with plenty of power to reach the satellite.  Then between the ELT and ADS-B, S&R will have a good idea of the vicinity I went down.  Once in the area, even in a valley in the trees and upside down, there should still be enough power for them to track the ELT.  With a destroyed external antenna a 20 sq mile dense forest is going to make it difficult to find me.  Even if it's a 5 sq mile block of trees, there's still a chance that they'd miss where I went through the tops of the trees.

Thoughts?  Learn from your experience stories?

 

One nice thing with 406 is that theres a red button on the panel (i have ack), and if you can remember to push that as you glide down, it will send out position reports before you even hit (and possibly rip off your antenna).  

[PeteMc]

14 minutes ago, Ragsf15e said:

it will send out position reports before you even hit (and possibly rip off your antenna).  

Yep, that was my point with the comment: I figure if something happens I'll engage the ELT at altitude and it should transmit with plenty of power to reach the satellite. 

You also have ADS-B which may or may not follow you down close to the ground in many parts of the country.  But all bets are off with ADS-B if you're in the mountains as you loose altitude, so not something to rely upon, just a potential extra bit of data.