Exhaust Shroud Replacement on BC-65

[SomethingScrewy]

Fellows,

I am the new owner of a 1940 BC-65. The airframe is outstanding, but over time it is going to need some work forward of the firewall.

The first thing to fail (just after I completed my insurance checkout and a solo flight, fortunately) was the exhaust stack, which broke off where it exits the cowling about flush with the end of the exhaust shroud. We pulled the shroud, and the IA and a welder say the rest of the piping is acceptable, and it can be repaired in place.

The shroud is another story, it is shot - we pulled it out in more than three pieces. Univair says their new one should fit, but I can tell from the product photo the flanging on theirs is different than mine (mine does not have an external flange, it was held together with worm clamps). I am going to order one and find out.

I've read all I could find on this topic in the forum archives, but still have some unanswered questions:

Assuming the Univair shroud does fit, can the new shroud be installed without removing the engine/mount? Perhaps by dropping the exhaust and maneuvering the pieces just so? Or is that effort futile, and I need to pull the engine/mount as would be necessary to remove the whole stack?

If the Univair shroud does not fit, what are my options? I had the thought to send the whole exhaust along with the new shroud to a shop such as Dawley Aviation or AWI to have them fabricate a new stainless steel stack that matches the old geometry but fits the new shroud. Any other suggestions?

Is there a particular salvage yard or enterprising individual that specializes in Taylorcraft pieces and parts?

Regards,

Lance

[sully]

Welcome to the forum. The shrouds can be removed. After fighting similar issues I removed the engine and mount one last time. Installed the Luscombe exhaust and have been very happy. See Terry Bowden for details.
https://dc65stc.blogspot.com/2010/09...onversion.html

Sully

[SomethingScrewy]

Sully,

I appreciate your reply. I have seen Terry's site linked in other posts on the topic, and by all measures the Luscombe exhaust appears to be a technically superior solution. If that becomes the only reasonable option, I will pursue it. However, the past several owners have invested in keeping the aircraft I now own in as original a configuration as feasible, so I do not mind spending a little extra to keep the exhaust original in appearance and sound. But I do want it flying again sooner than later. We shall see.

[mikerice]

I am in the throws of exactly your problem. We have the original Taylorcraft exhaust and I found a thumbnail-sized hole in the exhaust just as it exits the #1 cylinder. We elected to buy a new Wag Aero exhaust. We are going to remove the shroud and then fit it to the new exhaust. That's the plan, but plans don't always work out.

I have not pulled the old exhaust yet, but plan to do so this weekend. We have pulled the exhaust 2 years ago for a repair similar to yours and it is definitely repairable. even if you have to pull the exhaust, you know that shroud will fit. We still do not know if our shroud will fit the new Wag Aero exhaust. And our shroud is pretty ragged. Fortunately, we have a good sheet metal guy, so it is an issue of time to completion ( and getting back in the air.) I will try to remember to shoot some photos of our exhausts for comparison purposes, and the shroud parts (which can be removed and installed with the engine on the plane).

[Kerbs]

Lance, I may have something that will work for you. I just sent you a PM.

Stu

[astjp2]

You should get away from the factory exhaust and go with the Luscombe or Cessna 150 exhaust, it can be serviced and is STC'd/field approved and the factory system is prone to cracking...

[Scott]

I've heard that Aerospace Welding has a form to make the stock shroud but I've never confirmed it.

The Univair shroud, which is the one that Aircraft Spruce sells, is stated to only fit the Univair exhaust. The sticker shock stopped me from inquiring further.

I purchased the Wag exhaust and I have no complaints. It's mild steel but it was a third the price of the Univair unit (not including the shroud), so I can buy another two replacements and still be ahead! I stripped the paint off it and used a ceramic paint baked on with two heat guns. I also electroless nickle plated the tailpipe in and out, but these are just appearance steps as the pipe will corrode from the inside.

I ended up fabricating a shroud. Made the form from 3/4" plywood, used 6061-0 .040" for the top and bottom, 6061-T6 .040" for the tail pipe and flanges, and 2024-T3 .032" for the joggles to join the upper and lower halves. It was time consuming and somewhat tricky but I got a good result on the first attempt! (as opposed to the bungee covers that took 7 tries).

More details here:

http://c-fclr.blogspot.com/p/firewall-forward.html

Note that fabrication starts July 2017 ie scroll down about 1/4 of the way, then back to the top.

All of this assumes you want to stick with the stock configuration as I did.

I did make a couple of practical changes: 1 I did not split the tail pipe as per the stock unit. I have the top half, bottom half and tail pipe. To inspect the exhaust I remove 6 screws and 3 clamps, tail pipe slips off and the top half lifts away. Bottom half dangles while you inspect the pipe. 2. I used woven baffle seal material to make the connection to the steel intakes (welded to the exhaust) so there's no steel chafing against aluminium.

[SomethingScrewy]

Thanks for sharing, Scott. Beautiful work and it is great to see it documented so thoroughly on your website. Somehow I missed seeing yours at Oshkosh in 2018 - I was on the lookout for Taylorcrafts and only found one or two far afield in vintage. I was not able to attend Oshkosh 2019, but heard Taylorcrafts had quite a showing this time. Congrats on Grand Champion!

Regarding the Univair shroud fit - I talked to Univair and they disputed the claim that their shroud only fits their exhaust. They said their shroud is an FAA-PMA replacement for the original shroud, and therefore should fit any original exhaust or any replacement exhaust that conforms to the original. Wag Aero is the one making the claim that the Univair shroud will not fit the Wag Aero exhaust, but Wag Aero also claims their exhaust is an exact replacement for the original. When I asked the question to Wag Aero, they had no technical explanation as to why exactly the Univair shroud does not fit, saying only that customers have told them it does not. The ground truth remains elusive.

--Lance

[3Dreaming]

These airplanes were all basically hand built. Parts from one won't necessarily fit another even from the factory. It certainly is not a stretch that a shroud for one company will not for another's exhaust.

[astjp2]

Hell a 737 max is still basically hand built for a major share of it.

[Guest]

Thanks for sharing, Scott. Beautiful work and it is great to see it documented so thoroughly on your website. Somehow I missed seeing yours at Oshkosh in 2018 - I was on the lookout for Taylorcrafts and only found one or two far afield in vintage. I was not able to attend Oshkosh 2019, but heard Taylorcrafts had quite a showing this time. Congrats on Grand Champion!

Regarding the Univair shroud fit - I talked to Univair and they disputed the claim that their shroud only fits their exhaust. They said their shroud is an FAA-PMA replacement for the original shroud, and therefore should fit any original exhaust or any replacement exhaust that conforms to the original. Wag Aero is the one making the claim that the Univair shroud will not fit the Wag Aero exhaust, but Wag Aero also claims their exhaust is an exact replacement for the original. When I asked the question to Wag Aero, they had no technical explanation as to why exactly the Univair shroud does not fit, saying only that customers have told them it does not. The ground truth remains elusive.

--Lance

Regarding the blue text above-

I don't doubt what they said to you. I don't dispute what you are saying at all.

However I have experienced the same problem that you are describing with Univair FAA/PMA parts for other airplanes (Aeronca).

I have found cases where their parts will only fit with other Univair parts so if you replace most of the pieces everything is ok. But they do not fit with the original parts unless you modify the new Univair parts to fit.

Is that bad? Well it's not supposed to happen but it is a lot better than not having access to any new parts.

For me it ends up being economics. I stopped using some Univair parts because it costs to have them modified to fit (even if I do it myself it still costs something) and there are other sources that provide a part that does fit for a lower initial cost and no mods are required.

FAA/PMA does not guarantee a proper fit based on my experience because sometimes they reverse engineered the part and unknowingly do it from worn/damaged components.

I have seen one part that is an exact duplicate of a damaged part. It does not resemble the factory drawing for the part and absolutely does look just like the part that has been damaged in service. That one is not worth buying, just fix the damaged one that you already have! :-)

Dave R

[TimHicks]

When I first got my '46 BC12D 25 years ago, it had a mild steel exhaust and I had to replace the downpipe (where it exits the cowl, just like yours) twice in 5 years. I replaced the whole thing with a Stainless steel manifold (still original design) from an outfit in Jumping Branch, West Virginia. Fantastic results. Highly recommended. It has been maintenance free for 20 years.
In 2014, I moved that same exhaust manifold from the A65 to my new C-85. I had to make the spacing between the exhaust ports a little bigger. See the modification here: https://vb.taylorcraft.org/forum/tay...ust-Extension=
I'm totally glad that I went to Stainless steel earlier rather than later.

[mikerice]

I installed the WagAero exhaust and it fits as well or better than the original tcraft exhaust. It is mild steel and primed, so we will see how long the paint lasts.

The heat muff is worn out (primarily the ends where it fits to the steel "cuffs" on the exhaust). It fit the new Wagaero exhaust same as the original. The heat muff appears to be an original Tcraft part as there was a magic marker labeled Taylorcraft part number written on the inside. I straightened out the heat muff as well as possible and patched as best as possible, but it really needs about a half-inch added on both ends. I will test fly it soon.

[Robert Lees]

...

However I have experienced the same problem that you are describing with Univair FAA/PMA parts for other airplanes (Aeronca)....

I've also found the same problem with PA22 landing gear, landing gear fairings and all sorts of other PA22 stuff, all from Univair, very poorly when it comes to mating them up...and they're from the same supplier!

I know what they do: They get the TCDS (or PMA..whichever) and make them to the drawings. There is no consideration of these old drawings being accurate. I don't blame them, particularly: If they wanted to make everything fit, they would have to change the drawings.; guess what the FAA would have them do?

[Robert Lees]

I installed the WagAero exhaust and it fits as well or better than the original tcraft exhaust. It is mild steel and primed, so we will see how long the paint lasts.

....

I also have a new WagAero exhaust on my US Taylorcraft (my UK Taylorcraft has had a custom-built stainless one for over 27 years now,without a problem..same exhaust for 65 & 85...like Scott, I like the appearance & sound of the original configuration, even for the loss of breathing that could be improved by using a twin exhaust).

We'll see how long the PMA WagAero one lasts.