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  #1  
Old 04-15-2011, 09:28 AM
allbee allbee is offline
 
Join Date: Aug 2006
Location: spokane, wa
Posts: 805
Default exhaust muffler warning

First off I want to say that it hurts me to bash a supplier of parts. But in the interest of safety, I have to do this. I built my airplane with vetterman exhaust w/mufflers. Now at the moment I can't remember the cost of the mufflers, somewhere in the 500 to 800 dollar mark. Well if any of you remember I ran a thread that ran as: High egt on no. 1 and 2. In the last 3 weeks. I thought I found the problem with exhaust gaskets. Now it started out with 100degress hotter on egt with the peak on fuel setting going higher as well. Well my problem was irratic, would be there, than not. I went through everything a person could think of to find the problem. Than the problem got worse, now I have egt's over 1600 on 1 and 2(300more), 3 and 4 CHT's would go through the roof up to 420. egt on 3 and 4 just fine. CHT's on 1 and 2 ok, egt's through the roof. I also found that 1 and 2 were running real rich.

I went and did a pressure test and all cylenders were 76to78/80. I dialed the cam all fine. I pulled the rockers off the exhaust and found wobble up to .08 on all stems. I call bart and he says that that's pretty normal, that he has seen way worse and not cause a problem with high egt's. He says restriction in exhaust or timing. well can't have a problem with two systems on electronics. I go back to the hangar and just look at the engine. Than I follow the exhaust off the no1 it goes to no2 and than out the muffler. I say, you idiot, you dumm dumm. I huridly pull of the exhaust off the front of the muffler and look inside with my trusty light. OH MY GOD. Is all I could say. All the guts of this muffler is pushed to the back of the muffler and cut off the exit.

I call Larry. He says, get this, I've never seen this happen before, they usually brake apart and go out the end. Well I thought you bet, whatever, problem like this does happen to me. He tells me that I need to get the latest update done on my mufflers, call the place in CAL that does them for me. In fact just send them to him. I call this guy down in KALIFORNIA and he says the same thing, we never have had an exhaust plug up, they brake up and go out the back. Send them to me and we'll fix you right up, and OH these are normal wear items and it will cost 150 each to fit them with the new stuff. WHAT???? I just put this airplane in operation not even 2 years ago. I may have 460hrs but it's NOT my fault. I say ok.

I take my mufflers off and go back to the shop. I look inside and all the pieces on the left muffler are floating around inside, that would account for it happening one time and not the next. I knock the muffler on the floor and get the offending piece flat disc to the opening in front, no way this thing is comming out. So I fire up the cutting torch and cut it in two. I pull this out, than I get to the tube inside which is like a swiss cheese thing. I possision it and gut it with the torch. Fine and dandy I now have an expensive straight pipe.

I grab the still good muffler and there is no way to gut this thing out so I leave it. Now I have this thought, KISS(keep it simple stuppid) I no longer want mufflers, updated or not. Plus 300 on top of what I've paid already, I'm a little ticked to say the least. Not only that, I put myself on the line flying this thing with a plugged exhaust. It flew and if it wasn't for the Dynon ems I wouldn't have know it had a problem.

Anyway I put the mufflers back on the plane and flew it, wooohooo, what a difference, in fact it has never reached the speeds that I got and I still have the right side with an acting muffler. I guess I'll just have to go buy a straight pipe and replace it. Cuss, KISS is going through my mind at this point. The money originally spend, well safety is going to have to be paramount in this one I guess.

My advise to anyone running mufflers. Make your own AD and check these thing either every annual or 100hrs. What to check for, well cracks in the insides and make sure they look good. Mine rusted out and broke apart in big pieces. Good luck with your mufflers is all I can say.
  #2  
Old 04-15-2011, 09:50 AM
rv9aviator rv9aviator is offline
 
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Location: Arkansas
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Was the design changed at some point with an update? I have a new Vetterman setup with dual mufflers. It is about 4 months old and haven't done the first engine start yet but soon. Just curious.
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  #3  
Old 04-15-2011, 09:51 AM
aerhed aerhed is offline
 
Join Date: Dec 2008
Location: Big Sandy, WY
Posts: 2,567
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Calm down. The guts have been coming out of airplane mufflers since there have been airplane mufflers. I've seen empty muffler cans on EVERY spam can on the market. Inspecting the insides of mufflers has been on the Annual checklist for every airplane forever. Unlike a car, these things are close to the heat source and really get stressed. The quality on Larry's exhaust systems meets or beats every "factory" system I've ever seen. Sorry yours came apart but please, calm down a bit.
BTW, didn't Mike S. and I both recently post to check for exhaust "potatos"?
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  #4  
Old 04-15-2011, 09:56 AM
Mike S's Avatar
Mike S Mike S is offline
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Location: Dayton Airpark, NV A34
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Quote:
Originally Posted by aerhed View Post
BTW, didn't Mike S. and I both recently post to check for exhaust "potatos"?
Yep, but in a different thread, not in the one he posted.

I just re-read your thread about high EGT issued, and you mentioned you found the problem as being intake gaskets.

The high temps caused by the intake gasket issue could very well have caused the damage to the muffler guts.

And like was mentioned above, aircraft muffler guts failure is common. I had it happen to my Stinson a couple times.
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  #5  
Old 04-15-2011, 10:01 AM
allbee allbee is offline
 
Join Date: Aug 2006
Location: spokane, wa
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Quote:
Originally Posted by rv9aviator View Post
Was the design changed at some point with an update? I have a new Vetterman setup with dual mufflers. It is about 4 months old and haven't done the first engine start yet but soon. Just curious.
I was told that they made a change to a cone type. Still I'm not one to want to go through this again.

Mike,
Like I mentioned, this was intermittant and everytime I tried a fix it would clear on the next flight, than take another flight and it would come back.

I'm new to flying and owning airplanes so any thoughts on inspecting mufflers are NOT in this kids brain at all. I hope this warning helps people with mufflers in the future.
  #6  
Old 04-15-2011, 10:21 AM
aerhed aerhed is offline
 
Join Date: Dec 2008
Location: Big Sandy, WY
Posts: 2,567
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About half of the 182's flying out there have their flame cones missing from the muffler. Usually once they are gone you quit taking the muffler apart on Annuals and just shine a light up the tailpipe. Then you can say "yup still missing". You still need to pull the heat shroud and check the can's integrity. That's the big one because of CO leakage into the cabin. We're usually looking for the "Ballpark Frank Syndrome" i.e. "They plump when you cook 'em".
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  #7  
Old 04-15-2011, 11:41 AM
elippse elippse is offline
 
Join Date: Dec 2006
Location: Arroyo Grande, CA
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So, you're knocking out the inside of your mufflers so they don't work as mufflers anymore. That means you're carrying around a lot of extra weight that does nothing and probably adds extra back-pressure. So you really don't care how much noise your plane makes now, so let me make a suggestion. You can install short individual stacks on each cylinder exhausting through the sides of the cowling, and they can be arranged to actually do some augmentation if the exhaust actually helps pump cooling air out the side, too.
For those who are of the so-called "tuned exhaust" school of thought, let me quote the Bible on engines.
C.F. Taylor, Volume 1, page 201. "At a given speed, the length of the exhaust pipe can have an appreciable effect on px in eq 6-13 because of its influence on intensity of exhaust-pipe pressure waves, and their timing in relation to top center. However, in practice, it is found that the effect of changing exhaust-pipe length is usually small because the effect of changes in px on volumetric efficiency is slight."
Volume 2, page 400. "Reference10.801, p.48, states that the use of individual eexhaust pipes developed for racing purposes can increase volumetric efficiency by 5 to 7 per cent."
Proper design of the pipe, using impedance-matching formulae, can result in more power, and if used as augmenters, decrease drag, both of which will make you go faster!
  #8  
Old 04-15-2011, 01:06 PM
allbee allbee is offline
 
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Location: spokane, wa
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let me put something out here. I like to fly, I would like to be quiet as well. But after this experience, forget the quiet. When the big problem happened, apparently when the muffler plugged closed, the engine went from running not so bad to real bad real quick, lose of power overheating, you name it. All the inspections at anual are pretty much worthless when things let go. So my thoughts are more safety than anything else. Yes extra weight, so straight pipes are on the plan. But I have some nice speed and there may be extra weight, but hay! I been flying with that weight for 460 hrs now and use to it, so again, who cares at this point. I got my baby back and better than ever. Today I was getting 168kts tru airspeed at 1000 ft off and 50 rich of peak. top temps on the cht was 300 and on climb out 360. egt's were 1330. way back to normal. Again I state that if it weren't for the dynon ems I would have probably taken it on a trip 2000miles from home and had the problem come up and been completely screwed. Glad I found the problem.
  #9  
Old 04-15-2011, 01:55 PM
C-FAH Q's Avatar
C-FAH Q C-FAH Q is offline
 
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Location: Ontario, Canada
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Drop that nose wheel off and the true airspeed will go to 174
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  #10  
Old 04-15-2011, 02:03 PM
allbee allbee is offline
 
Join Date: Aug 2006
Location: spokane, wa
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ya I know, let me see what happens when I get that right side opened up on the exhaust. I don't want to drop the nose, like the front view and landing in high cross winds to much, sorry. although I do like flying my other plane which is a tail wheel, I like the rv the way it is.
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