Zenith Aircraft Builders and Flyers
ELT antenna replacement options
So it's time to replace my 121.5 ELT with a combination 121.5/406. The install of the ELT and cockpit wiring are pretty straight forward, but the replacement of the antenna has got me at a bit of a loss.
The ELT antenna itself is located on the top of the fuse just forward of the tail faring. I can't figure out how to get to it easily to get it out and the new one in.
After staring at it for an hour or two and talking it over with the other airport guys who are sympathetic with my plight we came up with a few options.
1. Disconnect the control cables and get someone skinny to climb back there and undo it. I'm not sure the skin will support the weight of someone in there, or if it's even feasible to climb past the flaperon controls. Looks barely doable and I would support the tail of the plane with some wood topped with foam. Still seems like a risk for damage. Has anyone done climbed back in there and come out unscathed?
2. Cut an access hole under the antenna and reach up from the underside. Looks like my arm would just be long enough. Probably wouldn't be a fun job and I don't necessarily like that idea too much.
3. Leave the ELT antenna as it is and install the 406 ELT antenna where the current com antenna is, then move the com antenna to a bent whip under the fuselage. This is probably the easiest option, even though a bit silly as it leaves useless stuff on the plane. But, least risk of damage.
Any other ideas or thoughts?
David Gallagher
Since the 601XL already has a lower access door as part of the design, I was surprised to see that you high wing guys did not have one. I'm sure it's a bigger job to incorporate one now, but if you wanted to, the 601XL design would likely be a starting point. You could ask Zenith if it could be a direct retrofit and follow their drawing. It's basically just a square sheet door, a hinge, some stiffeners and a bunch of nut plates. It has been very handy to pop mine open during inspections and when I retrofitted shoulder harnesses.
Dave G.
Jun 17
David J. Beaulieu
Another option...drillout the current doubler holding the antenna, cut and fashion an access panel which holds the antenna, reinforce as necessary, install with nutplates and done. (The access panel doesn't need to be centered on the top skin) Good luck with it, not a difficult job, though intimidating (at first) to consider cutting a large hole in the top skin...
Cheers! Dave
Jun 18
Nick
On the drive home from the airport I had an idea... Bordering on somewhat comical and not having much to lose, I bought one of those grabby tool extend-a-hand things and was able to undo the TNC connector on the antenna.
I've got some adapters and mounts 3D printing to get a wrench on the end of the grabby tool / broom handle to hold the nut and undo the antenna from the bottom. New antenna should drop right in and with the nut holder on the grabby tool I should be able to get the antenna in from the top and someone on the bottom holding the tool to thread it in.
It's a bit fiddly and cumbersome and kind of seems like weird keyhole surgery on the plane, but I think it beats putting an access panel in! Will report back with the rest of the results when I get to it later this week.
Jun 18