jamesm Posted September 16, 2021 Report Share Posted September 16, 2021 I am considering getting a newer 406 ELT. Currently I have a 121.5 ELT EBC, which has always bothered me. since the batteries 4 or 6 double 'AA' batteries glued together and tied in ELT signal generator with wire nuts. Should crash where ever to happen more likely the ELT would be obliterated on impact. Looks like there is about 4 different choices to choose from. I am curious to know people thoughts on the ELT and perhaps why they choose that particular 406 ELT? One my concerns is on how GPS position is being transmitted. In other words I know some ELT's have built in GPS and of course more money. But I have limited number of RS 232 GPS connection available to the 406 ELT for position. Hypothetical scenario (Yes I have an ADS-B but left out of the scenario ). Since I don't know how the 406 ELT transmits the GPS location. One thought I had was, If the 406 ELT is tied into your panel mounted GPS for the position to the ELT to broadcast. Should you ever have a crash and the GPS signal from the panel mount GPS is obliterated by the crash. Does the 406 ELT have some sort of buffer in the ELT that keeps the last known GPS position just prior to the crash and then broadcast last known position? Is it worth while to have a built in GPS on the 406 ELT? Does the 406 ELT's that have a built in GPS, have a RS232 serial port on them? (so you can see if the ELT's GPS position is correct), How do one verify the ELT's GPS position is correct? Without having an expensive test equipment? how is the check the 406 ELT at annual ? How long do the 406 ELT's batteries last ? The ones that I have seen online, seem to last 5 to 6 year at about $240 ish for the replacement battery. Are they easy to replace the ELT battery? Any other considerations that I should be aware of on the 406 ELTs ? Where to mount 406 ELT in a 67C ? ( preferably in a location easy to get at to change the battery every 4 to 6 years) Where to mount the external 406 ELT antenna if required ? What signal interference have people seen from adding a 406 ELT (if any i.e. GPS , Magnetometer, Com , Nav signal) ? I hate ask the last one. Has anyone had use their 406 ELT a side from bad landing or accidental activation? If so would there be lesson learned from the event that you wouldn't mind sharing? Thanks in advance, James '67C Quote Link to comment Share on other sites More sharing options...
PilotX Posted September 16, 2021 Report Share Posted September 16, 2021 Answered, in no particular order. I have had 406 ELTs with built in GPS (for redundancy) and recently installed in a 406 ELT in the Bravo. ARTEX has a lot of install manuals available for download, don't know about the other manufacturers. Mine receives location data from the 530. The battery packs should be good for 5 year or a certain defined amount of usage. WIth the ARTEX you can subscribe to a service which allows you to test the ELT on the ground to verify it is sending a signal but the installer will likely test it in accordance with the procedures in the manual. The drawback is you will probably need a ghastly external antenna and it will cost you 10 knots (maybe less maybe more but who really knows). Everything else being equal and slightly pudgy it was a slide in replacement for my old orange ELT in the tail, fortunately I have long arms, we did run new wires but reasonably simple, the tray had holes in it that lined up with the old ELT tray holes and so except for the wire, it was nearly a drop-in replacement unless you count installing a new antenna. Good luck. 1 Quote Link to comment Share on other sites More sharing options...
EricJ Posted September 16, 2021 Report Share Posted September 16, 2021 Functionally the RS-232 Rx can be connected to an existing RS-232 from the GPS source. I think my G5 and the ELT are wired to the same signal. You should be able to verify that it doesn't need a dedicated RS-232 in the install manual for the unit. In the event of GPS failure before or on impact, the ELT is supposed to transmit the last known GPS coordinate, perhaps also with a time stamp. Since they don't transmit unless activated, they shouldn't generate any interference with any other systems. Mine is in the tail on the avionics shelf, so easy to access for battery maintenance, etc. They're good systems and hugely more effective than a 121.5 ELT. 1 1 Quote Link to comment Share on other sites More sharing options...
PT20J Posted September 16, 2021 Report Share Posted September 16, 2021 I would be surprised if the whip antenna actually created much drag. Some think it looks ugly. The dorsal fin on my M20J is plastic and so Mooney folded the original whip antenna within it. But you can't do that with the 406 MHz antennas because they need to be mounted vertically. 1 Quote Link to comment Share on other sites More sharing options...
201Mooniac Posted September 16, 2021 Report Share Posted September 16, 2021 Mooney has instructions to mount the antenna under the dorsal fin for the 406 ELT but I don't have any idea how well it works when the antenna is in a horizontal position but that isn't an unusual position for the antenna to end up in after a crash. 1 Quote Link to comment Share on other sites More sharing options...
ZuluZulu Posted September 16, 2021 Report Share Posted September 16, 2021 34 minutes ago, 201Mooniac said: Mooney has instructions to mount the antenna under the dorsal fin for the 406 ELT but I don't have any idea how well it works when the antenna is in a horizontal position but that isn't an unusual position for the antenna to end up in after a crash. A lot of invasive metalwork is required and my shop quoted me an obscene, "please-don't-take-this" price. So I'm stuck with the stupid whip. This is what I had put in (when the old ELT failed recert). I do feel better having a 406 MHz but am hoping never to test its true capabilities. 1 Quote Link to comment Share on other sites More sharing options...
ArtVandelay Posted September 16, 2021 Report Share Posted September 16, 2021 But you can't do that with the 406 MHz antennas because they need to be mounted vertically. Why? Vertical antennas work great for horizontal transmissions, so a horizontal antenna should work great for vertical transmissions (it transmits to satellites, not ground stations). Quote Link to comment Share on other sites More sharing options...
PT20J Posted September 16, 2021 Report Share Posted September 16, 2021 Radio signals are either horizontally or vertically polarized. Remember the old VHF television antennas? The transmissions were horizontally polarized. That's why the home receiver antennas spread out horizontally. Rotate it 90-degrees and you wouldn't get much signal. The ELT transmission is supposed to radiate a vertically polarized signal omnidirectionally. This requires a vertical radiator. The ELT antenna is a quarter wave monopole with a ground plane. If you fold it over, the radiation pattern will be affected. AC 91-44A says to mount it vertically. My ACK E-04 manual specifies that it must be mounted within 30 deg of vertical in flight attitude. Probably Mooney's hidden design wasn't all that great from a RF perspective. Skip 1 Quote Link to comment Share on other sites More sharing options...
201Mooniac Posted September 16, 2021 Report Share Posted September 16, 2021 2 hours ago, ZuluZulu said: A lot of invasive metalwork is required and my shop quoted me an obscene, "please-don't-take-this" price. So I'm stuck with the stupid whip. This is what I had put in (when the old ELT failed recert). I do feel better having a 406 MHz but am hoping never to test its true capabilities. I can't seem to find the instructions right now but there is really minimal metal work involved. There is a small bracket to mount the antenna beneath the existing antenna hole. There is a lot of time required to remove the horizontal stabilizer fairings and the dorsal fin. The problem for me is I have really good paint and removing the fairings and fin will do some paint damage that I'm hesitant to have to get restored. Quote Link to comment Share on other sites More sharing options...
philiplane Posted September 17, 2021 Report Share Posted September 17, 2021 I favor the Artex ELT345. It accepts GPS coordinates from most GPS units. It's lightweight and easy to install. It's more rugged than the ACK ELT-04, which suffers from false alarms due to a twitchy G-switch. The ELT345 is reasonably priced, and has a long battery life, cutting the costs of maintenance. 1 1 Quote Link to comment Share on other sites More sharing options...
ZuluZulu Posted September 17, 2021 Report Share Posted September 17, 2021 2 hours ago, 201Mooniac said: I can't seem to find the instructions right now but there is really minimal metal work involved. There is a small bracket to mount the antenna beneath the existing antenna hole. There is a lot of time required to remove the horizontal stabilizer fairings and the dorsal fin. The problem for me is I have really good paint and removing the fairings and fin will do some paint damage that I'm hesitant to have to get restored. Maybe my shop just didn't want to do it then. Quote Link to comment Share on other sites More sharing options...
0TreeLemur Posted September 17, 2021 Report Share Posted September 17, 2021 My shop just installed the Artex 345 in our C. Ran two wires. One for the GPS signal to the 430, and the second to the test/arm/on panel switch. Yes, the whip antenna does look kind of dorky, but I can't see it when I'm flying. 1 Quote Link to comment Share on other sites More sharing options...
PT20J Posted September 17, 2021 Report Share Posted September 17, 2021 If you really hate the whip antenna, you could install one of these… 1 Quote Link to comment Share on other sites More sharing options...
PT20J Posted September 17, 2021 Report Share Posted September 17, 2021 Mooney SI M20-116 for installation of the Artex ME-406 appears to describe mounting the whip antenna beneath the dorsal fin. However, the SI states that the installation must be according to the Artex installation manual which states that the antenna must be mounted within 15 deg of vertical. 2 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.