This is probably really basic knowledge to those that know about these things, but I'm not one of those people. I found a 337 for putting 8.50 x 6.00 tires on my Champ. It's free for the downloading. Now what? Do I just do it? Does my IA or A&P have to be involved or what? Could someone point me in the right direction? I would appreciate any help.

Dave

A 337 is just the FAA form number for a major repair or modification. It gets filed with the FAA to record that you made such a mod.

A 337 can have a few different bases for approval:

STC – Engineering has been performed and approved by the FAA already. You are basically buying a sure thing. You supply your STC paperwork with your submitted 337.

Field approval – You are applying for a one-off modification by supplying ad hoc data and references to previously approved similar mods. This is where the 337 you downloaded comes in. You supply this with your similarly-worded 337 as a "follow-on" approval and hope your local FSDO agrees. They may be more scrutinizing than the FSDO that approved the old field approval, or it could fly right through.

DER signoff – This is where a designated engineering representative puts their butt on the line to say they've review the engineering of your mod and attest that it's worthy. Since few DERs will pencil whip this, it's usually expensive because they will actually do some engineering to CYA. I think. Edit: I've been corrected. DER can only provide approved data for use in a field approval.

All require your IA's info and signature.

That clears things up a bit. Looking for an easy way. Appears there isn't one.

Thanks

Dwr7ac wrote:.... Looking for an easy way. Appears there isn't one.Thanks

There aren't very many "easy ways" in aviation.
That said....the first thing to do is read the Champ TCDS (type certificate data sheet). #A-759.

https://rgl.faa.gov/Regulatory_and_Guid ... v%2073.pdf

I'm not sure what size tires you have now,
but the TCDS lists 800x6 4 ply tires as being approved on at least some 7AC Champs.
If applicable to your airplane, this change would just require a logbook entry & a revised weight & balance.
Also, American Champion has a factory approval for 850x6 4 ply tires,
which a friend of mine who owns a 7ECA used to put on a set of Desser smoothies.
It's not free, but as I recall he was charged a very reasonable fee for the paperwork.
If it's an STC, this would need a 337 filled out by an IA as well as a logbook entry & new W&B.

Either of those is just about as easy as it gets in aviation.

That helps. Think I'll contact ACA and see what they have.

Thanks

As I've stated several times on this forum, the STC for 4 ply 8.50 x 6 tires for anything on the A-759 type cert IS free.

Says so in the STC. Print it and hand it to your IA.

Hey!

Do you still have a copy of that field approval for the 8.50's x 6 smooth tires for the 7AC? thanks!