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**Len Petterson** · 01-25-2006, 19:14

Re: Leaky Wing Tanks

Look for this topic in the forum, I was in on doing this and it can be dune.

There is some pictures on this web site.
Len Petterson

**mhorowit** · 01-26-2006, 12:10

Re: Leaky Wing Tanks

Len - could you please point me towards the pics and the subject of the thread to which you were referring? REason I"m asking, there is a slight chance I might get a BC-65 and I"m thinking I'd like to add a 6 gal tank in the wing. Thanks, Mike

**N96337** · 01-26-2006, 12:20

Re: Leaky Wing Tanks

We covered the fuel tanks with aluminum on a Stinson once, and it definately did need a field approval! There was NO hesitation from my PMI that it would require one, so I'd submit a 337 to your local FSDO before I got too much further.
John H.

**Pearson** · 01-26-2006, 15:14

Re: Leaky Wing Tanks

I am really getting conflicting info about whether or not this needs a 337. The original IA that is going to supervise my work told me no to the 337. But I talked to another IA that agrees with you that a 337 is needed.

Isn't there a member of this list that works for the FAA? I wonder what his opinion is.

**N96337** · 01-26-2006, 15:26

Re: Leaky Wing Tanks

Call the FSDO in Renton, they'll be final word anyway. Or, ask your IA who his PMI is (primary maintenance inspector)... call that person. Otherwise, you'll wind up just like you say, in the middle of an annual and no 337.
John H.

**CraigH** · 01-26-2006, 19:58

Re: Leaky Wing Tanks

I'm not an IA, but can almost guarantee that mine WOULD NOT sign that off without a field approval. What I can tell you is that I would walk away from a purchase of an airplane with such a mod that didn't have a corresponding 337 and blessing from the FAA.

**Acroeric** · 01-26-2006, 22:28

Re: Leaky Wing Tanks

I know a faa inspector really well and I think it needs a field approval. It should not be any issue though. If you need help writing it up just let me know- I would be glad to help. Take a read of FAR 43 appendix A- it makes this pretty clear.

I have seen several that had this mod and never questioned how it was done- it did look pretty good though. Also- you may try to use the Swick STC as previously approved data- that STC uses aluminum covered wing tanks.

**Pearson** · 01-26-2006, 22:50

Re: Leaky Wing Tanks

I love this forum! Thanks Eric, and everyone else who responded!!! Part 43 appendix A spells it out loud and clear. I'll get a 337 on this modification.

**Yellow Duck** · 01-27-2006, 03:49

Re: Leaky Wing Tanks

What size alum is required. I have some .025, Would this be ok or to thin? Also where do you screw it to ? The Ribs on each side? What about the front and rear ?

Where is the thread showing this ?

I also have a left tank that is unuseable now and would love to pull and repair it. The alim cover would be great.

**whake** · 01-28-2006, 08:01

Re: Leaky Wing Tanks

We are in the process of covering the wing tanks with alum. using rivnuts. we are writeing a 337 that was pre approved by the local feds. the project should be complete by the middle of Feb.

**Yellow Duck** · 01-28-2006, 14:59

Re: Leaky Wing Tanks

Would love a few pic and copy if available. Had a bad spot on the bottom because of the leaking tank, Cut it out and put a patch, painted it today. A little rain hope it doesn't screw me up to bad. Went ahead and painted it anyway. Not the best patch and the paint is close but not a true match. Monday will sand and put another coat on.

Pulled all the inspection plates again ane double checked the spars. Looks very nice, fabric and ribs look nice also. Had some trash in the lift struts from the paint job a few yrs ago, have always meant to repaint them, sooo, guess I'll do it now. Sanded them down and took all the trash out, no rust. Prime and paint them next week.

**whake** · 01-28-2006, 20:03

Re: Leaky Wing Tanks

When complete I will post some pictures of the project. Should be a neat job the edges of the alum are bent down to form a seal

**Guest** · 01-28-2006, 21:48

Re: Leaky Wing Tanks

Originally posted by Pearson

I spoke to an IA today about cutting my wing tanks out to have the leaks welded up. I don't want to use tank sealer. When I asked about getting a field approval for covering the tanks with a sheet of aluminum instead of fabric, he responded that it would only require a "logbook entry".

Has anyone heard of such a thing being done with only a logbook entry? I don't want to have my plane grounded during an annual years from now because another IA doesn't approve of this "logbook entry". I thought anytime you "modified" an airplane it had to have at least a field approval or 337. Wouldn't replacing the fabric over the wing tanks with metal be considered a modification?

Yes, it is a modification or alteration. The 337 is needed for major repairs or alterations as defined in CFR PART 43 Appendix A. The issue is whether or not it is a major alteration.

There is some wiggle room in the interpretation of that paragraph. For instance if you can't find the original cap and have to put a different but suitable cap on the wing tank have you made a major alteration to the wing and need a 337 or just a log entry?

Or the self opening pitot covers many of us use, are they a wing major alteration? They are not in the aircraft specification and they are a mod to the wing, the pitot is part of the wing isn't it? Is it major and you need a 337? Of course not, just a log entry, most probably don't have even that.

It sometimes comes down to whether the licensed person doing the work considers the alteration to be a major one and there is often some room for judgement there. It has been a point of discussion at the IA meetings.

Last meeting I recall the FAA inspector stating that the A&P has to make that call and two folks may see it differently.

Sounds like your IA's are just reading it different ways. It could be that the one requiring only the log entry only is actually making the correct call. But as you suspect there is no telling that future IA's will be taking the same position wheter it be right or wrong it can effect you.

You won't get any complaints for putting in a 337 when it's questionable whether you really need one. It justs cost a little more.

If you do a major alteration you need some approved data one small source is AC43.13-2A, another is a field approval, AD's, STC's plus more

Hope this helps, Dave.

**Pearson** · 01-29-2006, 15:31

Re: Leaky Wing Tanks

Dave thanks for your input. It DOES help!

Walter Whake I sent you a private email concerning your 337. I would welcome any pictures and/or verbage you used to write up your 337.

I agree Dave, it is a matter of interpretation. But I like my annuals to go smoothly (cheap). Part of the reason I bought a Taylorcraft is because they are so low on maint.

Personally, I don't consider replacing a small portion of the fabric with a sheet of aluminum a MAJOR modification. But when I take it in for the annual, there is only one opinion that matters and it isn't mine. So I will get a 337, hopefully without fuss, and make all the IAs that do the future annuals happy.

Thanks again everyone for the wonderful input!!!

Last meeting I recall the FAA inspector stating that the A&P has to make that call and two folks may see it differently.

Sounds like your IA's are just reading it different ways. It could be that the one requiring only the log entry only is actually making the correct call. But as you suspect there is no telling that future IA's will be taking the same position wheter it be right or wrong it can effect you.

You won't get any complaints for putting in a 337 when it's questionable whether you really need one. It justs cost a little more.

If you do a major alteration you need some approved data one small source is AC43.13-2A, another is a field approval, AD's, STC's plus more

Hope this helps, Dave.

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