Is a non-TSOed ELT antenna installation considered unairworthy?

[ArVeeNiner]

There have been numerous discussions about ELT antenna locations over the years on this forum. One suggested that the ELT must be installed per the manufacturer's instructions because it is a required TSOed unit. However, from what I've seen, there seems to be a fair amount of flying RVs with antennas that differ from the recommendations, which tells me that they had no issue with their DAR.

Has anybody ever been refused an airworthiness certificate based on the ELT installation?

[Mike S]

I am also thinking about using a home made ELT antenna, so the timing of this is perfect.

Come on DARs out there, what is the answer here???

[flytoboat]

It seems to me that you should be more concerned with it being "crashworthy".

[elippse]

I just made a copper-strip 1/2 wave antenna on the inside of the fuselage curve just behind the baggage bulkhead. With its curvature it won't be as polarity sensitive as a vertical whip turned on its side. Maybe you could do something similar on the canopy behind you. Be sure to use ferrite core(s) over the coax near the antenna feed. As for your question, I guess you could use the whip supplied with the ELT if you're concerned.

[fl-mike]

Originally Posted by elippse

.... Be sure to use ferrite core(s) over the coax near the antenna feed. ....

Why would you want to do this?

[jferraro17]

Good luck. I've asked 3 DARs and gotten 3 different answers with regard to using the supplied ant., as well as the mounting location.

Joe

[RV6_flyer]

Ameri-King and ACK are the most popular C-91a 121.5 / 243 MHz ELTs that we use. You can use a different antenna with them as long as it meets the manufacturer's VSWR and other requirements. You still need to mount the ELT and antenna in an acceptable manor. See the ACK and Ameri-King web sites to download their manuals.

If you are going to install one of the new 406 MHz ELT, then you MUST use the antenna that is approved for it to be a legal installation. Approved typically means the antenna that came with it as there are not many alternatives.

Yes I am a DAR. Another DAR may have a different opinion. If I am wrong, please show me the link to the documment.

The ferrite (or 2, 3, or 4) at the end of the coax is to help stop reflections back into the transmitter. It is an OLD ham radio trick.

[ArVeeNiner]

I have an Ameri-King 121.5 model AK-450. I would like to mount the stock antenna high in the baggage compartment, behind the pilot. I thought that I would be able to argue that the instructions don't specify the outside of the aircraft but that is not so. There are two places in the instructions (page 9 of http://www.ameri-king.com/pdf/02&#37...n%20Manual.pdf) that indicate that it's to be attached to the aircraft skin or on the top of the aircraft.

Somebody indicated in the past that an ELT is not required for the Phase I testing. I looked up Sec. 91.207 of the FAR and found that:

"(f) Paragraph (a) of this section does not apply to--

(4) Aircraft while engaged in flight operations incident to design and testing;"

Not that I advocate the absence of an ELT on board, but, isn't Phase I AND Phase II considered testing? Certainly Phase I alone is a test period and therefore an ELT is not required, correct? So, if it is not required, is it reasonable to assume that it can always be added sometime before the end of the Phase I test program?

[elippse]

Originally Posted by RV6_flyer

The ferrite (or 2, 3, or 4) It is an OLD ham radio trick.

OLD? I resemble that remark!