My original AMOC request was for an .035 wall tube. The FAA engineer wanted me to use .049 as he didn't want to accept any credit for the original .035 1025 tube and a 3/4 .035 tube allegedly would not meet the strength requirements. Really didn't make much difference in my case as I'm only using a piece a little over 14".
Piper Rudder Airworthiness Directive Issued
- Thread starter Steve Pierce
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Mikey
FRIEND
Everett, WA
dgapilot
Am I correct that your “Major vs Minor” is from AC 43 Appdx A (b) which says that repairs, reinforcements, strengthening that utilizes riveting or welding is considered “Major”?
Thx. Mikey
Attachments
That and 14 CFR1.1 definitions and AC43-210A. pretty much anytime you weld you have a major repair.
bob turner
Registered User
Yes to all that, except I have not yet received the actual letter. They wanted a drawing, so I submitted one.
They declined on the "global" so I am restricted to six aircraft.
One mechanical engineer opined that my solution might be optimal. My personal skills as a mechanical engineer have atrophied - I had exactly one upper division course on strength of materials. But I personally believe that nested tubes develop the same bending strength regardless of method of attachment.
They declined on the "global" so I am restricted to six aircraft.
One mechanical engineer opined that my solution might be optimal. My personal skills as a mechanical engineer have atrophied - I had exactly one upper division course on strength of materials. But I personally believe that nested tubes develop the same bending strength regardless of method of attachment.
TR Dunn
FRIEND
The method of attachment is relevant when the member (nested tubes in this case) is subjected to transverse shear because differing methods have differing shear values. The shear stress is transferred to the “method” (weld, mechanical fastener or chemical bonding agents). The “method of attachment” must therefore meet the calculated shear load. If the “method of attachment” fails in shear, the nested tube/s no longer meets the design moment of inertia (resistance to bending).
TR
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bob turner
Registered User
Got a reference for that? None of the sources I used for my calculations addressed that issue. It does seem intuitive.
bob turner
Registered User
Just got my approval letter. It doesn't look at all like the one that Alex got, but then it is not "global." I get the impression that it would not work for a Super Cub. My letter says basically nothing about how to do the repair. It simply references my application documents.
Folks, this was a lot less of a hassle than the average Field Approval request. It was educational in several ways, and involved a fairly satisfying excursion into things like "area moment of inertia" and Young's Modulus. Great fun!
Folks, this was a lot less of a hassle than the average Field Approval request. It was educational in several ways, and involved a fairly satisfying excursion into things like "area moment of inertia" and Young's Modulus. Great fun!
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Steve Pierce
BENEFACTOR
Graham, TX
So can you post your AMOC or describe it please.
bob turner
Registered User
Yes. It is rather long, especially the part with the math. The essence is - an .049 wall tube of minimum length 41" is coated with an approved adhesive (not JB Weld) and jammed in until only enough room for the tailwheel steering arm remains. Then, after the adhesive has cured, hot linseed oil is poured in and drained.
Joe Zuklic was very nice during the entire process, and guided me along the way. He really wanted a drawing and an appendix showing my calculations. He did say the engineers were concerned that a good bond might not be attained, but that they thought it would be ok for the J3 and J4 types. That is why it is not global.
I am going to send him a thank-you note, and ask about the process for adding other aircraft. I think I have your e-mail somewhere . . .
This was all new to me - I stumbled a bit during the process. The application is not sent to the engineer - it goes to a specific address noted in the AD. They log it in and forward it to the engineer. It should be in an instructional format, with an appendix for calculations, and a drawing.
Joe Zuklic was very nice during the entire process, and guided me along the way. He really wanted a drawing and an appendix showing my calculations. He did say the engineers were concerned that a good bond might not be attained, but that they thought it would be ok for the J3 and J4 types. That is why it is not global.
I am going to send him a thank-you note, and ask about the process for adding other aircraft. I think I have your e-mail somewhere . . .
This was all new to me - I stumbled a bit during the process. The application is not sent to the engineer - it goes to a specific address noted in the AD. They log it in and forward it to the engineer. It should be in an instructional format, with an appendix for calculations, and a drawing.
hotrod180
FRIEND
Port Townsend, WA
So, glued-in only with no mechanical fasteners or welds?
Steve Pierce
BENEFACTOR
Graham, TX
It isn't going anywhere, adehesive or not. My daughter and I test fit a liner tube in a Gas and a Tig welded rudder. Took two of us.
Removed the rudder from our PA-14 today. Followed the process to check with 70% nitric acid. The test came out clear so when the plane was rebuilt in Canada the rudder must have been replaced Now a log book entry and we are all set. Thanks to everyone who posted info. and Ideas.
