A confounding question, any guesses at the answer?

[Guest]

Hi all,

I ran across an interesting question this spring.

It all started when I submitted some samples of my 337's for unattached components to the FAA.

Things went fine but there was one comment. It was that there was no reference to approved data for the replacement by welding of a steel tube.

Well it turned out that I have the approved data for that but reference to it was either edited out by mistake or just forgotten. I use 337 PDF templates for that work so they can get changed by accident.

I edited the template.

However I got to wondering about that basic comment and came up with a question as many of you probably have too.

Let me elaborate.

Imagine that you have a damaged diagonal tube (could be any tube really) and you decide to cut out the damage and splice in a new piece. AC43.13-1B can be used at approved data for that repair.

Alternatively imagine that you decide to remove the entire tube and replace it. In that case what is the approved data? I can't find mention of any such thing in AC43.13-1B, it only covers "partial replacement".

Sure if you have the fuselage drawing you can reference that but no one ever has that drawing.

I asked an FAA guy about this. He knows that it is done but had no answer. I asked a second FAA guy, no answer.

What do you think that the answer is?

I am tempted to request an interpretation from the FAA legal office.

Dave

[astjp2]

Re: A confounding question, any guesses at the answer?

Please do not open this can of worms, contact the ACO in anchorage and ask for Dave Swartz. He can answer your question. Tim

[astjp2]

Re: A confounding question, any guesses at the answer?

Dave Swartz, Anchorage ACO (907-271-2671, [email protected]), or

[Mark Julicher]

Re: A confounding question, any guesses at the answer?

I opened that work can (more like a bucket of worms) a while back.
First, I was pounced upon by a Fed for using the term "approved data" because AC43.13 is only "Acceptable Data". Gotta love those lawyers.
Second, I welded in a tube and referred to the welding procedures but sort of omitted the bit about partial repair.
43.13-1B Ch 4 paragraph 4-91b " Unless otherwise noted, welded steel tubing may be spliced or repaired at any location along the length of the tube." I know that is not "air tight" authorization, but it was enough for me.

Good luck on your 337s.

[astjp2]

Re: A confounding question, any guesses at the answer?

43 changed to approved data at the last rev. Its approved if there is no data from the manufacturer....ie Cessna vs. Taylorcraft. Tim

I opened that work can (more like a bucket of worms) a while back.
First, I was pounced upon by a Fed for using the term "approved data" because AC43.13 is only "Acceptable Data". Gotta love those lawyers.
Second, I welded in a tube and referred to the welding procedures but sort of omitted the bit about partial repair.
43.13-1B Ch 4 paragraph 4-91b " Unless otherwise noted, welded steel tubing may be spliced or repaired at any location along the length of the tube." I know that is not "air tight" authorization, but it was enough for me.

Good luck on your 337s.

[Garry Crookham]

Re: A confounding question, any guesses at the answer?

--------------------------------------------------------------------------------
Advisory Circular
U.S. Department of Transportation
Federal Aviation Administration



Subject: Acceptable Methods, Techniques, and Practices – Aircraft Alterations
Date: 3/3/08
Initiated by: AFS-300
AC No: 43.13-2B



1. PURPOSE. This advisory circular (AC) contains methods, techniques, and practices acceptable to the Administrator for the inspection and alteration on non-pressurized areas of civil aircraft of 12,500 lbs gross weight or less. This AC is for use by mechanics, repair stations, and other certificated entities. This data generally pertains to minor alterations; however, the alteration data herein may be used as approved data for major alterations when the AC chapter, page, and paragraph are listed in block 8 of FAA Form 337 when the user has determined that it is:

a. Appropriate to the product being altered,

b. Directly applicable to the alteration being made, and

c. Not contrary to manufacturer's data.

[Ragwing nut]

Re: A confounding question, any guesses at the answer?

Your thinking too small. Anything less than complete replacement of a part is "partial replacement". So what if you replaced the whole tube. It is still considered a repair whether you replaced 1" or all but 1". AC43 or any other publication or approved data will not tell you how much or how little you can replace. There is no manufacturer approved repair manual to tell you where to stop for taylorcrafts that i am aware of.

[astjp2]

Re: A confounding question, any guesses at the answer?

I am thinking that the airframe is the NEXT HIGHER ASSEMBLY for part number and you can replace the whole tube or multiple tubes as a repair....actually the cub guys replace the whole airframe except for 1 piece from the original and call it a repair...Tim

[PA1195]

Re: A confounding question, any guesses at the answer?

I've had flaps rebuilt from just the remaining hinges as a repair. Looking back through my Taylorcraft logs and 337's the fuselage tubing and landing gear truss was both repaired and had tubing replaced. But that was the '70's when folks just got the job done. Now there's more paper than metal in the project.

I wonder if folks overthink this whole process and fret too much over repairs to an airplane.

Gary

[Mark Julicher]

Re: A confounding question, any guesses at the answer?

Gary,
Point Well Taken! I missed that little nuance.