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How Not To Do It

Steve Pierce

Steve Pierce

BENEFACTOR
Graham, TX
I see a lot of stuff done incorrectly for what ever reason and thought it might be an informative thread to see what kinds of things people find so that others won't make the same mistakes.

This is an oil pressure line run from the right side of the firewall to the engine. Great idea, shorter run etc. however you now have to disconnect it when you swing the engine for normal maintenance. It is also in the way of getting the engine mount bolt back in.
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Those holes drilled in the exhaust pipe to muffle should be through both pieces to retain them. Some folks in Florida got killed several years ago when someone used a hose clamp instead of the proper exhaust clamp with the tit in it.
Never seen the hole in the slot before, probably not gonna work too well.
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Steve Pierce said:
I see a lot of stuff done incorrectly for what ever reason and thought it might be an informative thread to see what kinds of things people find so that others won't make the same mistakes.

This is an oil pressure line run from the right side of the firewall to the engine. Great idea, shorter run etc. however you now have to disconnect it when you swing the engine for normal maintenance. It is also in the way of getting the engine mount bolt back in.
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The other thing that is wrong with this picture is that there is no loop in the oil line to absorb shock from the engine vibrating on the mount.
 
No loop needed with the flex line. Originally Piper did it like this except they used cooper tubing instead of aluminum. This way it swings with the engine.
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Small continental exhaust nuts
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Little washer side of it goes up to the exhaust
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I use those small Continental brass exhaust nuts on Harley Davidson Evolution engines. I also use them on small Continental engines.
 
Cub junkie said:
I use those small Continental brass exhaust nuts on Harley Davidson Evolution engines. I also use them on small Continental engines.
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I'm trying the long ones on my experimental I0-360 Cub. The long ones cover all the stud threads, which should prevent the studs from eroding outside the nuts as they normally do. The DAR questioned them and liked my idea.
 
The 10-32 machine screws that hold the fuel tank covers to the leading edge and false spar are supposed to only be 1/2" long so they don't damage the spar cap.
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This muffler made it through two annual inspections by two different shops, and I mentioned to both that I was getting exhaust in the cabin. The cracks are right where the hose for the cabin heat exits, 180 degrees from the seam in the shroud, pretty hard to get to. So, even with good mechanics, things get missed. We fixed everything else it could have been, but sometimes the most obvious solution is the correct one.

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moneyburner said:
This muffler made it through two annual inspections by two different shops, and I mentioned to both that I was getting exhaust in the cabin. The cracks are right where the hose for the cabin heat exits, 180 degrees from the seam in the shroud, pretty hard to get to. So, even with good mechanics, things get missed. We fixed everything else it could have been, but sometimes the most obvious solution is the correct one.

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You were lucky. It could have been worse. http://www.supercub.org/forum/showthread.php?20658-URGENT-!&highlight=muffler+split
 
Steve Pierce said:
Those holes drilled in the exhaust pipe to muffle should be through both pieces to retain them. Some folks in Florida got killed several years ago when someone used a hose clamp instead of the proper exhaust clamp with the tit in it.
Never seen the hole in the slot before, probably not gonna work too well.
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Wow, thanks for this Steve!! Not quite sure what an exhaust clamp with a tit in it looks like, could you put up a photo of one please? I'd like to compare it against the ones I've got. Thanks!!
 
moneyburner said:
This muffler made it through two annual inspections by two different shops, and I mentioned to both that I was getting exhaust in the cabin. The cracks are right where the hose for the cabin heat exits, 180 degrees from the seam in the shroud, pretty hard to get to. So, even with good mechanics, things get missed. We fixed everything else it could have been, but sometimes the most obvious solution is the correct one.

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Just to confirm I'm seeing this right, is the crack running along the top of the tube towards the mid right and angling up from left to right?
 
Philly5G said:
Just to confirm I'm seeing this right, is the crack running along the top of the tube towards the mid right and angling up from left to right?
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It runs in the same direction as the flow aligned with the screw hole in the flange, starts about 1/2" to the left of the flange weld. There is also a diagonal crack branching off from it about a third of the way to the right. It's worse than the photo shows - it's open about 1/8" and the inside of the muffler can be seen through the crack.
Sorry for the poor quality photo.
 
moneyburner said:
It runs in the same direction as the flow aligned with the screw hole in the flange, starts about 1/2" to the left of the flange weld. There is also a diagonal crack branching off from it about a third of the way to the right. It's worse than the photo shows - it's open about 1/8" and the inside of the muffler can be seen through the crack.
Sorry for the poor quality photo.
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WOW and thank you!!! Yes, that’s the line I was looking at, although it looks nowhere near 1/8” wide!!!

If I needed convincing, that’s further convinced me to wrestle the muffler and heat shroud off and out and check the muffler every x hours!!!

Thank you :)

Philly
 

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So how did those folks in Florida die? I have had exhaust systems crack and/or fall off, and usually a precautionary landing, followed by a trip to the welder, saves the day.

I have not figured out how to get the muffler off of a Cub without un-doing at least half the stacks. I now insist on Atlee's mufflers for just that reason. Cannot imagine it falling off.
 
Thanks. I have worried about that stainless fuel pressure line on my Decathlon. Even bought an electric fuel pressure gauge to eliminate the line, but then found out it did no such thing - still needed the most vulnerable part of the line.
 
I have found stainless lines ready to chafe through and I have had a customer have a stainless line fail at the baffling union, that one spewed fuel for God knows how long. He said his fuel flow went way down and when I took the cowling off it was pretty clear what his problem was. This "Customer" refused a prebuy and I ended up doing a lot of work to get it airworthy. This fuel flow issue was the first time I saw the airplane. The guy was lucky to be alive.

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I would be more frightened, except that every Lycoming IO has those lines leading to injectors, and they seem to last a long time.

It is, however, tempting to block off that gauge line. At least one local aircraft has had a fire due to fracture of the gauge line, immediately after engine overhaul.

The report did not seem to say exactly what failed, only that the hot exhaust burned through that line, and that they found hose clamps.
 
bob turner said:
I would be more frightened, except that every Lycoming IO has those lines leading to injectors, and they seem to last a long time.
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Yes, and those have very reliable silver brazed compression style fittings on the end. in this case, the line in question was the one that sends the fuel to the pressure sensor that interpolates the pressure into fuel flow indication. it terminates in a flare and this is the part that failed. I will try to find the image of the one from a 185 that was worn almost all the way through. It was pretty scary too. Mostly because I was about to ferry it across the country.
 
moneyburner said:
This muffler made it through two annual inspections by two different shops, and I mentioned to both that I was getting exhaust in the cabin. The cracks are right where the hose for the cabin heat exits, 180 degrees from the seam in the shroud, pretty hard to get to. So, even with good mechanics, things get missed. We fixed everything else it could have been, but sometimes the most obvious solution is the correct one.

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That is why I remove the exhaust on work aircraft, remove the muff and then pressure test. I now have a US customs account for shipping from Acorn up in Canada...we reject a lot of exhausts.
 
bob turner said:
I would be more frightened, except that every Lycoming IO has those lines leading to injectors, and they seem to last a long time.

It is, however, tempting to block off that gauge line. At least one local aircraft has had a fire due to fracture of the gauge line, immediately after engine overhaul.

The report did not seem to say exactly what failed, only that the hot exhaust burned through that line, and that they found hose clamps.
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Well that pesky AD for the line inspection may not agree....
 
Had my #2 and #4 exhaust pipes unbolted to swing out of the way for cylinder #4 removal recently and was looking for the exhaust hose clamps with the nipple. The ones installed did not contain such retention mechanism. I have LEES so not sure if that has something to do with the absence of a hose clamp with a nipple or not.
 
A PA-12 flies SO MUCH better with a short mount! 3200 hours with long mount -12 and 900 hours with a short mount one. One of the best modifications for a PA-12 you can do. Its a little tight against firewall for maintenance, but with the swing mount it really is not a big deal. Moves the CG to a really good spot for all phases of flight. I thought it was not a big deal until I bought @stewartb plane and it is very significant.
 
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