Replacing a 121.5 ELT with a 406 ELT

[dbaran]

If a 121.5 ELT in a CAP Cessna is replaced with a 406 MHz ELT, is anything more than a logbook signature necessary (i.e., is a form 337 required)?

The maint shop says that a 337 is NOT required.  This was backed up by National.

The Wing DOV says that a 337 is required.  The Wing DO thinks it is required.

In terms of effort, I believe it was 14 hours of labor to run wires and install new antennas.  My own plane has STCs in the logbook for such trivia as different hub caps, sun visors, and fuel injectors, so it seems to me that you get a 337 for pretty much anything.

Does anyone have any direct knowledge (i.e., "Our plane had this done and we were given a 337") as to what the correct answer is? 

(I would like to avoid calling the FAA if I can on this one )

[Thom]

If a 121.5 ELT in a CAP Cessna is replaced with a 406 MHz ELT, is anything more than a logbook signature necessary (i.e., is a form 337 required)?

The maint shop says that a 337 is NOT required.  This was backed up by National.

The Wing DOV says that a 337 is required.  The Wing DO thinks it is required.

In terms of effort, I believe it was 14 hours of labor to run wires and install new antennas.  My own plane has STCs in the logbook for such trivia as different hub caps, sun visors, and fuel injectors, so it seems to me that you get a 337 for pretty much anything.

Does anyone have any direct knowledge (i.e., "Our plane had this done and we were given a 337") as to what the correct answer is? 

(I would like to avoid calling the FAA if I can on this one )

Unfortunately, the ONLY opinion that truly matters in this whole thing is that of your local FSDO.  They will make the determination, hopefully using clear guidance from FAA National.  Regardless of what anyone else thinks, the FAA has the final say.  (Unless you want to include the NTSB Judicial Review and Federal Judges and such, and I think we all want to stay far away from all of that...)

So, easy answer, ask the FAA. They don't bite, really.


Thom

[bosshawk]

I second what Thom says: the only authority that counts is the FAA.

Your wing DO and DOV have absolutely no say in this matter: in fact, the DO isn't even a pilot.

[bosshawk]

One addition: a better authority, if you insist on asking CAP people,  would be the DOAM, Gary Cinnamon.  He works with maintenance issues every day.

[dbaran]

I actually wanted to get an answer before the FSDO people showed up since we had a plane grounded.  They have gone off to research the answer; I guess it isn't that obvious.

[bosshawk]

Dave: I assume that the barn door is still open on this.  I checked with the IA who does the work on our 206, which has a 406, and he tells me that the new ELT comes with an STC, which then requires that a 337 be made out and filed.  A log book entry is required, as is a new weight and balance.

YMMV, since you are dealing with a specific FSDO and it seems that each FSDO in the US arrives at different conclusions on any specific question.

Good luck.

[dbaran]

Thanks - that is what I was curious about (what other people have). I took a poll at the meeting tonight, and both of the check pilots (one who is also an A&P) thought a 337 was required.

Our local FSDO is OK with just a logbook entry (no 337).  However, we checked around and about half of the CAP airplanes that have 406's came with a 337, and the other half with just a logbook entry. 

I guess it only becomes a problem if the plane gets moved to a different FSDO that wants the 337. 

[simon]

Kind of important to have a definitive and consistent answer from the controlling authority given that this will eventually impact 1/4 million aircraft* once 406's are mandated.

It is interesting to me that the FAA was so bent on pushing 406's but didn't think about this issue.

So far we have a definitive but inconsistent answer from the controlling authority - It varies between FSDOs - and the same from sources without the authority - CAP National, Wing DOV, DO, IAs, right down to the maintenance shop.

The safe route is as usual the most expensive and time consuming one.

* http://www.fas.org/sgp/crs/homesec/RL33194.pdf

[simon]

Something to add after my discussion with an A&P just now (DB - you know who I am talking about).

337: "Form, fit and function." This may be the terminology that makes it difficult to assign a blanket ruling on the upgrade from 121.5 to 406.

The two examples I was given are as follows:

1. A 121.5 to 406 upgrade for a Bonanza from a manufacturer that involved removing the 121.5 unit from the bracket and swapping back in an upgraded unit from the manufacturer that used the same bracket, same wiring, interface adapter, power supply, panel switch, antennas etc. In other words, same Form, Fit and Function. Under the regs., this should not require a 337 but should simply be a logbook entry.

2. A 121.5 to 406 upgrade that has just taken place in our CAP plane. This particular AP went and inspected it and told me that the bracket that was installed was heavy duty (Looked like custom sheet metal fabrication), had about 30 screws holding it in place, that the antenna was changed, then you have drilling into the airframe, new wiring, and the kicker - a new electronic box added that interfaces with the GPS. This, in his opinion, was not the same Form, Fit or Function (The GPS interface esp.) as the 121.5, Plus there wasn't documentation on the airworthiness of the unit re the GPS connection. So this case would necessitate a 337.

Perhaps this is the way it will go and may still be open to interpretation. Again, it is an interesting question given the widespread affect across the fleet.