Can someone who is well versed in modifications and repairs explain to me the 337 process? For any official types out there - these questions are purely hypothetical in nature - though poignantly relevant to some guy I know. We're not talking about radical experimental shit here - these things are apparently approved on other planes via various STCs and other guys are flying them with shit-eating grins on their faces. Thanks for your help.

I've read through this:

http://www.faa.gov/aircraft/air_cert/design_approvals/field_approvals/field_approv_proc/

But I still have questions that I hope someone can help me understand:

1) Do all 337s get approved by the FAA before they are allowed to proceed? In other words the A&P will not do the work, sign the log book and then wait for 337 approval, right?

2) The FAA link says that approval is indicated in block 3. Some guy I know pulled CDs on airworthiness from the FAA on several planes and all of them have blank section 3s - nothing de-nada. Does that mean they were approved?

3) What's the significance of the conformity section 6? This is as far as I can tell the only signature or marking approval - and all the ones I've reviewed show nothing from the FAA - only and IA - even for major alterations. If section 6 is signed - does that mean that section 3 was approved by the FAA?

4) How do you know if you "own" an STC - is there official paperwork with seals and signatures from the STC owner? What if a 337 was filed with data that claims "duplication" - is it sufficient to just have a copy of the STC that is downloaded from the internet?

4) Is the FAA CD the "end-all" record? If an owner has a copy of a 337 that was supposed to be filed and approved - but it does not show up in the FAA CD, is there some other search that is needed to be performed? Is the record solely by a/c serial #? If plane registrations change (N Numbers) - will all the records show up?

5) What if there is a log book entry that says that a 337 was filed by an A&P IA but there is no copy of the 337 with the (current) owner nor on the FAA CD? Can another be filed or it just like starting all over again?

6) What are the ramifactions of flying with work that is supposed to be approved under 337 field or STC approval but you only have a log entry with the IAs signature? If one gets ramp checked and dragged down the the fisdo and it sorts out that the work is not approved, what happens? Is the owner grounded until repairs are reversed or paperwork sorted? Is he/she tarred and feathered and forced to undergo sterilization surgery? Is the plane sold on the open market to reduce the national debt?

'soyAnarchisto

I can't answer your questions specifically, but my airplane has probably more 337s than most--seems like everyone makes pieces and parts STCs for 172s but they forget to list P172Ds on the AML, since it's a relatively rare version--and it's on the 175 type certificate (same as the XP) rather than the 172 type certificate. So just about every time my IA adds something for me, he has to go through the 337 process, even something as simple as wing tip strobes. Fortunately, he has a good relationship with the FAA in Denver, so it's not usually a problem, although sometimes it causes delays. In some cases, he's started the work before getting the approval, anticipating it will come pretty quickly, and other times he waits because he's not sure. But the airplane doesn't fly, and he doesn't sign it off, until the FAA approval comes. Could he sign off and could it fly before then? I don't know, but I don't think so.

For sure, I don't want to be accused of flying something technically "unairworthy", even if it is actually safe to fly. I was suspended for 90 days many long years ago for flying an unairworthy airplane, and I'm not interested in going through that again.

Cary

So do you follow up with the FAA for every mod and make sure it is on the CD? Or do you trust your log book entry and the copy of the 337 your a&p hands you?

I have not followed up. I have seen most of the 337s, although perhaps not all, but honestly I have relied on trusting my IA a lot. He's so darned meticulous that he's earned my trust.

Cary

In my recent search for an appropriate TD, I have come across(heresay) several situations where there is no existing paperwork(drawings, etc) for an approved STC or 337, which makes for a sticky situation w/ the Feds. NOTE: Always get appropriate paperwork(drawings, etc) for any mod.

My airplane has a Lyc 320 conversion & a taildragger conversion. The work was done years ago and was properly logged & 337'd, but over the years some of the supporting paperwork for the STC'd mods have gone AWOL. This does not make my airplane illegal or unairworthy, but it would make it tough if I ever had to document the fact that the mod's were done in accordance with the STC. Also might make it tough if I ever have to make any repairs without having the all the drawings & parts lists. I could maybe get fresh documents, but that might not be easy as the ownership of these STC's have changed hands a few times in the meantime.
So those of you doing mods to your airplanes, save ALL the paperwork- for the sake of future owners' sanity if not for your own.

Hence my question - what is the basis for your decision that you are airworthy? The logbook entry with the IAs signed? The photocopied 337 form in your possession that doesn't have a signature or stamp from the FAA? I know it's the owner/operator/pilots responsibility to asses airworthiness - but how far am I supposed to go and with what data? Am I supposed to go part number by part number and verify that the A&P did what he was supposed to and match it up with what's currently on the plane? How the hell can any pilot or owner reasonably do that - even if they were A&P IAs themselves?

This brings me to another question. How can one verify that an IA is really who he says he is. There's a number there in the log book next to his name - but can/should I call up the FAA or look it up online to make sure he's real or was real at the time he made the entry? How can I find the IA from a modification that was done in 1958? He's probably 6 feet under ground. What's to stop some unscrupulous yahoo from just writing a random number in there with a fake name?

Believe it or not - there doesn't appear to be consensus on this - among A&Ps or pilots - and this guy I know is afraid to ask the FAA for "help" - for fear of opening up the can of worms further. He thinks hes good - his A&P thinks hes good. The last 2-3 A&Ps think he is good over the last 10 years. He posts a picture of his plane on the inner toobs and some random comes out of the woodwork and points out something he and his A&P didn't catch - and asks if you have paperwork for that. Panic ensues at the disco.

You guys have a lot more experience at ownership than me. This is my first rodeo. I'm trying to understand the rules of the game and how to play it. This guy and I are discussing over beers - but this scenario exists and is very real and potentially serious to the people who might be involved - the money is real and the safety issues are real - what do people do?

Troy Hamon wrote:http://faa-der.blogspot.com/2010/02/not-all-337s-are-field-approvals.html

That's a good point. Not all 337's are field approvals. Keep in mind that a 337 is filed for every STC'd modification that's installed or applied to the aircraft, which is why some of the 337's on file for your aircraft have nothing in the approval box. The approval is implied based on the supplement to the type certificate.

The 170 I owned had a large number of 337's in its logs, most of which were STC'd modifications, not field approvals.

Soy,

You're asking a whole bunch of different questions.

First of all, a form 337 is nothing but a document that is submitted to the FAA to document a "major alteration".

It is up to the A & P or IA who submits the 337 to verify several things:

1) The basis for this modification...is it based on the provisions of an STC? If so, you'll need the permission to use that STC from the STC holder, and it needs to spell out the serial number/tail number of the airplane it's being installed in. A number of years ago, the FAA would sometimes sign off STC'd mods with just a xerox copy of the stc paperwork, but no more. If the mod is STC'd, it is the responsibility of the installer to verify that this particular modification won't negatively interact with other modifications....the mod has to be compatible in other words. That's one of the things the installer signs off on. Then the installer fills out a form 337, and submits it to the FAA. The FAA doesn't have to sign it or approve it....the STC already approved it.

2) If the basis is a field approval, I personally would NEVER permit a mechanic to even start an installation requiring a field approval UNTIL the mod has been approved by the FAA, either a FSDO Inspector sign off or a DER sign off. THEN you do the mod, and you submit the form 337 to the FAA, stating that the work approved in yada yada field approval has been completed. Again, it's the responsibility of the mechanic to verify compatibility with other mods, etc.

3) To be legal to fly, the airplane must be in conformity with it's type data and it must be in a safe condition to fly. GENERALLY, we take the IA's word that the airplane conforms to it's type data. It's not a pilot's responsibility to verify that every AN bolt is the proper size, etc in an airplane prior to flight. That said, if your IA is signing off a plane that clearly has missing paperwork, I'd be really hesitant to fly it, and I'd be looking for another IA.

4) If a 337 has been submitted to the FAA for a modification, it SHOULD be in the CD that the FAA will sell you. If it's not, and the signed form is in the airplane's paperwork, it'd get it submitted to the FAA.

5) If you're thinking of buying an airplane, and you can't verify the legality of a number of modifications, don't walk away, RUN.

MTV

soyAnarchisto wrote:6) What are the ramifactions of flying with work that is supposed to be approved under 337 field or STC approval but you only have a log entry with the IAs signature?

mtv wrote: 5) If you're thinking of buying an airplane, and you can't verify the legality of a number of modifications, don't walk away, RUN.

99% of the time, the reckoning comes when a potential buyer does his/her due diligence, not from the FAA. Unless there's an accident investigation.

It is also used for a major repair, when nothing is being altered.

I'm sorry - I know I threw a lot of questions out there. Let me see if I can be a little more specific with a couple of clarifications:

1) If I go to the FAA web site and type in my N-number or serial #- and I pay my 10 bucks - and they send me a CD - and i don't find everything there that I expect - is there another search I can or should be doing? That's it, right? There's no other database or research service that I'm not aware or right? I went here to get a copy of the aircraft record:

http://aircraft.faa.gov/e.gov/ND/

2) If I read a 337 from the above record search - and there is nothing in Section 3 - does that mean that there must have been a STC if the mod/repair is not on the TCDS? Section 3 indicates a field approval, right? If i don't have in my possession specific STC information indicating approval for my serial # OR something was installed or repaired that is specifically called out on the TCDS then I have a problem.

Do I have this right?

1) If I go to the FAA web site and type in my N-number or serial #- and I pay my 10 bucks - and they send me a CD - and i don't find everything there that I expect - is there another search I can or should be doing? That's it, right? There's no other database or research service that I'm not aware or right? I went here to get a copy of the aircraft record:

That's correct, as far as the FAA's concerned all the information submitted to them about your airplane will be in that record.

2) If I read a 337 from the above record search - and there is nothing in Section 3 - does that mean that there must have been a STC if the mod/repair is not on the TCDS? Section 3 indicates a field approval, right?

That's correct too. Block 8(back of a Form 337) of the 337 should be on your CD as well and that's where you will find an outline of the work performed, including STC# etc.

I deal with a lot of old airplanes and it's interesting to note how the amount of information required on 337s has changed. Way back when a 337 was required every year, signed by a federal inspector for the annual inspection! For many years,50s-60s-70s Block 8 might just read "Installed IAW STC #"and that was it.

Tracking down some missing, ancient STC paperwork has driven many nice people crazy.

Now when a 337 is completed block 8 can get very lengthy. AC 43.9 outlines what is required to be recorded.

Another interesting read (not really) is FAA Order 8100 which is the workbook an inspector is required to follow when making a field approval.

It's important to remember the Form 337 is for both Major Repairs and Alterations.

A couple points that may help......
1. 337s are required for "Major repairs or Alterations."
2. The Major repair part does not require any faa sign off. (As long as it was done in accordance with approved data.)
3. The Alteration part includes STCs and Field Approvals.
4. STCs do not require faa sign off.
5. Field Approvals require faa sign off.
6. AIs are not required to research the planes info in Okie City. They are required to have all the information available to them, to make sure the plane meets airworthy requirements. In other words, if the paperwork, (337s) are available, no further research is required.
7. Stcs are not required to be serial numbered. Most of the newer one are. The older ones were not. The serial number thing was started so the STC holder could make money reselling the paperwork. That's all. 337s for STCs are mailed directly to Okie City. No one looks at them. It's a copyright thing, not a faa thing.
All the info you need is in the FARs. It's a little hard to find, but it's there.
I'm an old guy and make mistakes. If I'm wrong on any of my post, please list the correct FAR.
Thanks.

Halestorm wrote:....Now when a 337 is completed block 8 can get very lengthy. AC 43.9 outlines what is required to be recorded. ....

I have a couple recent ones where the required "instructions for continued airworthiness" take up way more room than the description of the work performed. Can you spell o-v-e-r-k-i-l-l ?

soyAnarchisto wrote: Hence my question - what is the basis for your decision that you are airworthy? The logbook entry with the IAs signed? The photocopied 337 form in your possession that doesn't have a signature or stamp from the FAA?.......

In a perfect world, an IA's signature in box 7 "approval for return to service" should the determining factor whether an airplane is airworthy with that mod or repair.
As far as researching IA's, if they are current you can do it. If it's an old 337 from back in the day, good luck with that. I doubt the FAA maintains certificate data forever.
Some of your questions & comments have me wondering if someone involved in your situation is a lawyer. IMHO there is no such thing as a perfectly legal airplane if it is more than a year or two old. If you use enough of a fine-tooth comb, you can always turn up SOMETHING on the airplane that is not right or a t that isn't crossed in the paperwork.

hotrod150 wrote: Some of your questions & comments have me wondering if someone involved in your situation is a lawyer. IMHO there is no such thing as a perfectly legal airplane if it is more than a year or two old. If you use enough of a fine-tooth comb, you can always turn up SOMETHING on the airplane that is not right or a t that isn't crossed in the paperwork.

I am not a lawyer - and neither is this guy I drink whiskey with. I have no idea if the other random guy on the internet who is pointing out things from pictures he sees "wrong" is a lawyer or not - but he sure seems to claim to know a lot about "legality" and "airworthiness." He could be a FED for all we know - I know him no better than I you.

Man I want to go fly... waitin' for a seized up 1946 tachometer to get rebuilt myself.

soyAnarchisto wrote:Hence my question - what is the basis for your decision that you are airworthy? The logbook entry with the IAs signed? The photocopied 337 form in your possession that doesn't have a signature or stamp from the FAA?
....................... How can one verify that an IA is really who he says he is. There's a number there in the log book next to his name - but can/should I call up the FAA or look it up online to make sure he's real or was real at the time he made the entry? How can I find the IA from a modification that was done in 1958? He's probably 6 feet under ground. What's to stop some unscrupulous yahoo from just writing a random number in there with a fake name?........

Regarding the photocopied 337 with no FAA signature/stamp-- only a field approved mod would need that. FAA sign-off not required for an STC'd or otherwise approved mod, or a repair.
A fake signature from 1958? Come on....seems to me that's much ado about nothing. If it's been flown regularly & kept airworthy since then, that's over 50 annual inspections where nobody had a problem with it. I'd say you're good to go.
If the A&P's and/or IA's who have been involved with the airplane think it's OK, then by God I bet it is. If you're worried about what somebody on the internet says, picking apart the airplane and/or it's paperwork, #1 ignore the guy & #2 quit talking about it on there. Some people just seem to enjoy raining on other's parades. I don't know what kind of airplane it is or which site that's happening on, & I don't think I wanna know. But I have seen that sort of thing happen before. It might also be that the guy is honestly wondering what the "basis for approval" is, for whatever reason, and you;'re reading too much into that curiosity.

Only slightly off-topic...your bird predates the FAA and the FAR's. It was certificated under CAR-3. Those are the regulations that apply to its continued airworthiness. They aren't necessarily super-different. But they are different. And part of your ownership learning experience might be to study up enough to understand some of the differences.

The reason this is only slightly off-topic is because some things that need the super-duper FAA okey-dokey stamp to be installed in a FAR certificated airplane can be installed as minor modifications in CAR-3 airplanes, especially panel stuff...(within reason...tread carefully...read the actual regs...).

Be careful, but study up.

The important thing is to recognize the things that make real safety issues versus the things that just make confusing paperwork issues. If it is a real safety issue, don't dink around, get it fixed. If it is just a 1950's idea of how approvals should be recorded or obtained, I would not touch it unless there is a problem.

IMHO.