ELT Antenna

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Tbopper
Posts: 8
Joined: Sun Dec 09, 2018 7:15 pm

ELT Antenna

Post by Tbopper » Mon Nov 04, 2019 4:34 pm

FAA inspected our Pietenpol Air camper for it’s air worthy certificate yesterday.. Came down to the last question, where is the ELT. After a quick look a rejection was received. The ELT was out dated. The Frequency of 121.5 is no longer monitored. We bought a new 406 MHz ELT to install. The antenna for the old 121.5 ELT is midway between to rear cockpit and the tail post. To get to it will require cutting into the fabric, inspection ports. QUESTION Can the antenna for the 121.5 ELT be used for the 406 MHz ELT? It would save us cutting into the side of the fuselage if it can be.

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taildrags
Posts: 283
Joined: Tue Mar 07, 2017 10:39 pm

Re: ELT Antenna

Post by taildrags » Mon Nov 04, 2019 11:36 pm

Tbopper, it is my understanding and belief that the use of existing 121.5 Mhz ELTs is not prohibited... only the manufacture, importation, and sale of them, and of course the certification of any new models of them. Therefore, I believe your inspector was in error in denying your registration on the use of an existing 121.5 Mhz ELT. If he/she told you that the frequency of 121.5 Mhz is no longer monitored, then they were misinformed and they gave you misinformation about that as well. While it is true that the frequency is no longer monitored by the Cospas-Sarsat satellite network that formerly monitored the frequency, there are land-based stations which still monitor the frequency.

All of that said, it sounds like you are committed to the change to 406 Mhz. There are antennae such as the RAMI AV-300 that are listed as operating at either 121.5, 243, or 406 Mhz. It makes sense to me that the same antenna could be used for 121.5 and 243 since they are multiples of each other, but the 406 comes out as 3-1/3 times the 121.5, so I don't know the relationship between those wavelengths. You would do well to get in touch with a local amateur radio operator who might be able to help you with that.

Oscar Zuniga
Medford, OR
Air Camper NX41CC, A75 power

Tbopper
Posts: 8
Joined: Sun Dec 09, 2018 7:15 pm

Re: ELT Antenna

Post by Tbopper » Tue Nov 05, 2019 9:09 pm

Thanks for the information. We also was under the impression that the old ELT could be used and it came quite a surprise to us to get the rejection. We have already bought the new ELT and starting the installation with hopes we would not have to cut into fuselage.

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auburntsts
Posts: 4
Joined: Fri Nov 08, 2019 11:32 am

Re: ELT Antenna

Post by auburntsts » Sat Nov 09, 2019 6:28 pm

Your inspector was correct. For new installations an ELT has to meet TSO 129 (aka a 406mhz ELT) IAW 91.207 and AC 91-44A. 121.5mhz ELTs (TSO C91a) are still legal for existing installations but those days are numbered.
Todd Stovall
PP ASEL-IA
RV-10 N728TT
War Eagle!

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