Exhaust

[3Dreaming]

Does anyone know of a 337 for the installation of a Piper Cub exhaust on a BC12-D?

[Ragwing nut]

Which one? and why? and no I don't.

[PA1195]

I'd not install a PA-11 exhaust for example on my plane. There's better available for both heat and power.

[3Dreaming]

The airplane already has the exhaust, with the lower cowling made and cut to match. It has likely been on there and working fine for 20+ years. I would rather try and get it approved than spend the money to change it out.

[Ragwing nut]

sounds like 337 is in order. I would call FSDO and see what they think. I see it as form/fit/function. But they may not see it that way. In the old days we had a couple good FSDO guys that would see that and say "well its been there that long, I guess its proven to work", and sign it off. Not the case anymore.

[3Dreaming]

I called the FSDO, but they are closed with the government shutdown. Also the guy I would have liked to deal with retired last month. Not sure if there is anyone left with any common sense.

[Hank Jarrett]

I had an FAA guy looked at my Taylorcraft exhaust and said I wasn't allowed to use a home made exhaust without it being approved. I was kind of shocked, since I have an original equipment exhaust. He had never seen any exhaust on a Cont 65 except on a Cub so he thought he was an expert. I had to show him several Taylorcraft parts books with pictures of the stock exhaust to prove to him mine WAS stock.
There be idiots out there. Be very careful! ;-)

Hank

[Guest]

Contact DER Terry Bowden and have him create approved data for you is one way to do it.

You can look him up on this website or his own.

His is called Certified Aeronautical Produts => http://dc65stc.blogspot.com/

Dave R

[PA1195]

Have you determined what exhaust is installed? "Piper Cub" systems may have varied by aircraft model and engine and AD's may apply.

Edit: Dave's suggestion about involving a DER would be my first choice.

Gary

[Scott]

Based on my albeit limited reading, I get the sense that FAA is interested in getting out of the decision business in favour of the oversight (Transport Canada doing the same). From one perspective this is good because you can make decisions based on your reasonable interpretation of the available data and regulations etc. From the other perspective it's not so good as you still have the old-school inspectors that like to control, and then some owners/mechanics prefer to have the regulator make all the decisions (the perception being the regulator then accepts the responsibility).

SO, During our recent discussion on fabric attachment, I came across this relatively recent FAA AC43-210A document that provides a very useful decision tree that takes some of the subjectivity out of the major repair/modification determination process. It uses the word "appreciable" which is a great word to see in a process like this as it does allow for some common sense IMO. It also indicates to me that what was once a shoe-in for requiring a field approval, is not necessarily the same now.

Maybe this helps, maybe not, but given the Piper exhaust is a PMA part, I would be interested in your thoughts after applying the decision tree (first file) to your exhaust question Tom.

[3Dreaming]

Scott, CFR part 43 appendix "A" list changes to the exhaust as a major alteration. That brings me back to needing an approval.

[Scott]

Are you changing an exhaust? Or replacing one PMA part for another?
Your not actually making changes to an exhaust which I agree would be a modification requiring some engineering and potentially testing. The exhaust you have is clearly approved for use on the engine so the only real modification is to the cowling. No appreciable change to the key criteria laid out in the AC.

anyway I'm in no position to argue one way or the other, but regardless, using the regulator's own published decision process should eliminate some of the potential push back with a 337 submission if you decide you need to go that route.

[Guest]

deleted

[3Dreaming]

Are you changing an exhaust? Or replacing one PMA part for another?
Your not actually making changes to an exhaust which I agree would be a modification requiring some engineering and potentially testing. The exhaust you have is clearly approved for use on the engine so the only real modification is to the cowling. No appreciable change to the key criteria laid out in the AC.

anyway I'm in no position to argue one way or the other, but regardless, using the regulator's own published decision process should eliminate some of the potential push back with a 337 submission if you decide you need to go that route.

I bought a Taylorcraft that needed the engine overhaul and annual inspection to get it back flying. It has Cub exhaust that likely been running on the airplane was restored several years ago. I want to make sure I have the paperwork in order, so I am not hanging myself out there when I sell it.

[PA1195]

What current exhaust P/N's are on the Taylorcraft?

Gary