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ELT / PLB (merged)

Thanks - that's really very interesting. That's an FCC regulation, not an FAA regulation. It seems like a possible conflict between bureaucracies in the use of the word "use".

The FAA must be interpreting "use" as meaning new installation. The rest is surely the case, you can't buy a new 121.5-only ELT now.

At my base today, If I were to walk around and look at a great number of aircraft (hundreds), most would have a 121.5 only ELT unit. Those having a 406 unit would be a tiny fraction by comparison. It'll become apparent if the 406-MHZ upgrade ever becomes FAA mandatory, and by that time I suppose they'll be relatively inexpensive and few will object.

As of 2009, 121.5 MHz and 243 MHz signals are no longer processed by the SARSAT satellites. 121.5 MHz ELT would only work in countries with their own national infrastructure - I only know of UK and some regions of Russia. 243 MHz may be also be handled by the military. The only global frequency is now 406 MHz.

LKBU (near Prague), Czech Republic

Some basics on ELT. An ELT is required in a US registered aircraft. It may comply with either TSO-C91a (121.5 MHz/243 MHz) or TSO-C126 (406 MHz). An ELT certified to TSO C91 without the "a" suffix is an obsolete version of the TSO and after 6/21/95 may not be used in a new installation, but may continued to be used until it dies. The FAA never made any attempt to require a 406 MHz ELT. When SARSAT stopped reporting the 121.5/243 MHz ELT activations, that is enough to prod many N registered owners to upgrade to a 406 ELT, even though it isn't mandated. The vast majority of 406 MHz ELT's that have been installed also have a 121.5 MHz TSO-C91a ELT function built in. The satellite notices the 406 MHz, but all air SAR activity is based on homing in on the 121.5 signal. If the 406 ELT has GPS input, then homing isn't necessary. Not all 406 ELTs have this capability, but I wouldn't have one installed that didn't have GPS input. The advantage is that you don't have to wait for a pass of a LEO satellite to determine an approximate position. Any GEO satellite that has a receiver can provide an alert and a position within minutes of activation if you have a GPS input.

Then along comes the FCC without coordinating with the FAA bans the 121.5 MHz ELT. Totally studpid on their part as most 406 ELTs also have a 121.5 function and the FAA has not banned 121.5 MHz ELT's, so in effect they banned all ELTs, thus grounding all airplanes. Needless to say, this stupid rule was rescinded forthwith.

Regarding installation of the ELT requiring an STC, I submitted a question the FAA Chief Counsel on this point and asked if the guidance in AC 43-13-2B. Their conclusion was that the installation of an ELT was most likely a minor modification. I will send Peter a copy of the FAA ruling as I can't figure out how to attach a pdf file.

KUZA, United States

The file is here.

Great stuff

The only way to post images or files here (or almost any other public "discussion" site really) is to upload them somewhere first and then post a link to them.

There are very few "public" sites where one can post "binary" files i.e. files which are not images. There used to be loads but most have been shut down for hosting bootleg software etc. I can host files in a couple of places I own or control, which is what I did above. We can also host files here, under Articles / Tech Resources if they are "standalone" documents or articles. I might actually do that with this one, because it is really important.

For "casual" images, imgur.com is a good easy site.

Administrator
Shoreham EGKA, United Kingdom

@NCYankee

Thank you for your very informative post!

YSCB

This is a very interesting item and I have to say it shows my lack of detailed knowledge in some areas. I am (Ithink) a good aircraft operator and quite an intuitive pilot so it is amazing to see the level of detailed knowledge one can gain from here. Anyway, the ELT in question is an ELT-100 part no. 453-0150. It seems to have been made by ARNAV Systems. Inc. If anyone can point me in the right direction for a direct replacement it would be just great. Many thanks.

UK, United Kingdom

It's hard to get anything concrete on an "ARNAV ELT-100" which tends to suggest it is very old (pre-internet) and the company my not be around anymore, but google / images finds that this may be a fairly common old type of ELT.

The AK-451 (installation manual) seems to be the same footprint but does 121.5+243+406 so would meet any new requirements. 243 is redundant but that doesn't matter.

A data sheet is here (from google as usual).

However I have not been able to get a data sheet on the ELT-100 so can't be sure the footprint is the same. Anyway, the mounting is not an issue; structurally it should be a Minor mod (assuming the existing ELT installation was done correctly) unless somebody is ripping you off.

The Kannad unit (see my writeup) does 121.5+406 at about half the price of the AK-451.

OTOH an "ELT-100" can be this unit from ARTEX.

Googling on 453-0150 says this is not an ELT-100 but an ELT-110 - example.

Can you post a photo of the unit and the label?

Administrator
Shoreham EGKA, United Kingdom

Thank you Peter, this is the best image inview of the location.

UK, United Kingdom

I don't recommend anything from AmeriKing, terrible support. The best and the least expensive (Less than $600 USD) on the market IMHO is ACK and it provides a GPS interface, so if you have a GPS that provides a serial output, it can be mated to the ACK-04. This is what I have installed in my Bonanza.

KUZA, United States

From your photo, the ELT is certified to TSO C-91a, which is still permitted in the USA. If you are required to replace it with a 406 MHz unit, this has to be a mandate from your local authority, not the FAA.

KUZA, United States
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