For all you guys that are sick of hearing me harp on ELT stuff, go ahead and roll your eyes now. Okay, that's done.
The pics above show your ELT tray mounted sideways. If it's just sitting there and not installed yet, my bad. If not, look at page 41 of the install manual. The arrows inside the tray need to be within 10 degrees of the long axis of the fuselage. And be aware that the mount location of all the 406 mhz ELT's must be extremely rigid. For this, see page 38, paragraph F.
As for the antenna, see page 42, paragraph B. It states that the antenna is to be installed vertically.
That's the book stuff.
After seeing a number of crashes up here, where the ELT never activated, and seeing the way many ELT's are mounted, I'm firmly convinced that the flimsy mounting is a big factor. If the mount is not rigid enough, it will flex or give enough to dampen the impulse of the crash. Remember: the new ELT's use accelerometers NOT mechanical G-switches. The test procedure for triggering the ELT differs from the old style, also. The old ELT's could just be smacked with the heel of your hand or bumped against the bench and they would trigger. That will never trigger a new style ELT. For those, you need to use a throwing motion. Grab it with both hands and throw it away from your body and snatch it back quickly. This will trigger the accelerometer (provide it's not broken).
And even if the ELT says it will trigger in multiple directions, they all have a specific direction they need to be mounted. Some have arrows on the unit or tray and some just say to mount the face forward. But all have specs for keeping the unit mounted within so many degrees of the longitudinal axis and most have a spec on allowances for tipping the unit up or down.
Stick antennas are designed to be mounted vertically. They work straight up or straight down. Just keep them vertical. If you could look down on an antenna and see the signal radiate, you would see the signal look like an expanding doughnut, starting at the antenna and just growing larger and larger. If you lay the antenna on its side, the 'doughnut' is also turned on it's side. Now, instead of seeing a growing ring, the signal looks more like a figure 8. Strong signal to the left and right but extremely weak at the tip and base. Also, these antennas need a ground plane under their base to work correctly. That means square inches of surface not just a ground tab or wire. I prefer using stainless screen glued to the inner surface of the fabric as the ground plane, then mount the antenna in the center of the screen. Another problem with mounting the antenna inside the fuselage is that you are surrounding the antenna with metal tubing. That makes a sort of Faraday cage (google it) around the antenna. At best, this will decrease the strength of the signal from the antenna. If you use metallic (aluminized) dope, on your fabric, it will make it worse. The most popular place to mount them up here, is just forward of the vertical stab. That way, if you nose over, the vertical will give the antenna some protection and hopefully the antenna remains vertical, also. If you end up upside down with the vertical crushed, there is probably no sense in worrying about it.
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