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andyb

Exhaust Departed in Flight

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Today I was flying with another pilot, and after 3 routine legs, I saw that the exhaust had apparently broken off.

The flights and landings were absolutely normal, in the sense that there was nothing that would have suggested a problem or anything that would remotely have seemed that it could have precipitated this.

I'm at a loss for words.  Is there any history of this happening? 

Andy

CT Cowl.JPG

CT Cowl-a.JPG

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Well that sucks.  I had one break a few years back at a weld; the welds on the exhaust system are not great.  But that doesn't look like it's at a weld.  Are all your exhaust springs in place?  Seems like something vibration must have caused.  Or could it have been hit by something at some point?

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I have seen the face of the end of the muffler in the area of outlet pipe develop cracks which would have resulted in losing the pipe if this had not been detected and repaired.  The outlet pipe is a long arm which develops large forces where it connects to the muffler when it responds to engine vibrations.  Some CT's have a reinforcing brace welded between the outlet pipe and muffler face to dampen vibration of the outlet pipe and prevent the pipe from flexing the face.  Some CT's have the outlet positioned away from the center area of the end further towards the outside where the stiffer area resists cracking caused by flex.  You are not the only one to experience this.  If I'm not mistaken, I believe that there is at least one thread on this forum where this is discussed.

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This is on a CTLSi, and the pipe is clamped onto the muffler. I can attest that all of the springs were attached at the condition inspection, because I installed 8 new springs.

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Tom, after reading your comments I went back and took a closer look at the pictures.  I now see a clamp and it appears that there is maybe a part of the outlet pipe that is still clamped to the muffler.  Hard to tell but it appears that the outlet pipe has fractured a few inches out from the muffler and the end of it has fallen out and away from the CT?  This is a much different failure mode than anything I've seen.  I have no experience with CTLSi other than the one which my friend owns.  To my knowledge he has had no failures like this but he will want to check his outlet pipe after seeing this forum entry!

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My tailpipe broke at the elbow with less than 50 hours on a 2008 LS. Flight Design replaced it.

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1 hour ago, procharger said:

Is the exhaust burning that light or is it flash from camera? Or that

engine is really running lean?

The fuel injected engines do run leaner.

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Hi Tip.  Hadn't heard of your type of breakage.  Weird that this would break @ 50 hrs.  Maybe it had a crack when bent and formed?  Do you have a clamped or welded pipe?  

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This isn't the first time. I have seen another CTLSi exhaust pipe come off and fry the cowl, coolant reservoir and surrounding soft parts. I HIGHLY recommend that all CTLSi aircraft put a wrench on the clamp that holds the pipe in place and then drill a hole through both pipe and receptacle and put a stainless steel rivet in place. I have suggested the rivet to FD and this will make sure this never happens again. I have found a few clamps that needed to be loosened, pushed the pipe back in as far as possible and most of all tighten the clamps TIGHT.

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I'd recommend that this joint be designed with a "marman clamp".  Both the muffler flange and the exhaust pipe have flared ends and the clamp which is used is a "U" section which compresses both flares together when it is tightened.  This was developed for a long lasting and almost leak free joint for gas flow systems.  Very secure but if breaks are occurring at low hours, perhaps even this won't be foolproof.  That exhaust pipe must really be dancing around when looked at with modal analysis.

https://www.ebay.com/i/262837735762?chn=ps

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4 hours ago, Roger Lee said:

This isn't the first time. I have seen another CTLSi exhaust pipe come off and fry the cowl, coolant reservoir and surrounding soft parts. I HIGHLY recommend that all CTLSi aircraft put a wrench on the clamp that holds the pipe in place and then drill a hole through both pipe and receptacle and put a stainless steel rivet in place. I have suggested the rivet to FD and this will make sure this never happens again. I have found a few clamps that needed to be loosened, pushed the pipe back in as far as possible and most of all tighten the clamps TIGHT.

Roger, a screw or rivet wouldn't have helped here. His pipe broke in the bend radius.

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Your right no help in breaks. I had a hard time with the picture. Guess my eyeballs are getting older faster than the rest of me? Breaks either come from bad welds or excessive vibration.

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My CTSW had #1cyl exhaust pipe break at 600 hrs, middle of pipe not on weld. I wonder what alloy is used. SAE 321 stainless on certified aircraft don't seem to have a lot of issues except for high time systems. 

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It's a good thing that it doesn't crack on the weld, it means the weld is done properly.

Keep the ball joints lubricated. That's the biggest cause if the joints sieze.

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