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  #1  
Old 03-19-2013, 08:02 PM
BigJohn BigJohn is offline
 
Join Date: Nov 2008
Location: Gloversville, NY
Posts: 1,470
Default Exhaust blow-by

I'm in the process of performing my second condition inspection. I found that there has been some significant leakage of exhaust gases from the right rear exhaust pipe muffler joint. See photo. I will have to remove the muffler and investigate of course, but wondering if anyone else has seen this?

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  #2  
Old 03-19-2013, 08:35 PM
Bruce Russell Bruce Russell is offline
 
Join Date: Jul 2008
Location: Clayton, GA
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BigJohn,
I had this same issue on my first -12. I hired a Rotax Certified A&P and did a 100hr inspection with me "riding along". First thing is pull the muffler and clean the ball ends of the exhaust pipes and the sockets on the muffler. Next CAREFULLY bend the spring tabs so that the springs will have increased tension when installed. This will hold the ball and socket together with increased pressure. Before you reassemble the exhaust, put a healthy coating of Permatex Anti-seize(the grey/silver paste) on each of the muffler ends of each exhaust pipe. This will provide some sealing of the joint and make it easier to disassemble for later maintenance. Also, it looks like your springs might have some heat damage from the exhaust leak. My guy recommended replacing them since each spring is only about $3 a spring. I did all of the above with my mechanic and the exhaust leak went away. Please be careful bending the spring tabs as any muffler that has seen a few heat cycles could have brittle welds that can break if disturbed. Hope this helps.
-Bruce
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Last edited by Bruce Russell : 03-21-2013 at 08:15 AM.
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  #3  
Old 03-19-2013, 08:50 PM
NASA515 NASA515 is offline
 
Join Date: Nov 2011
Location: Hansville, Washington
Posts: 536
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Wow - that is "significant", John. How often do you pull the lower cowl?

Just wondering of the PITA part of the cowl installation process resulted in less surveillance than would be the case if more easily removable.

Bob Bogash
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Finished my airplane today - 1 year and 2 days.
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  #4  
Old 03-19-2013, 09:53 PM
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Geico266 Geico266 is offline
 
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Location: Huskerland, USA
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There doesn't appear to be much tension in those springs.
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  #5  
Old 03-20-2013, 06:58 AM
BigJohn BigJohn is offline
 
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Location: Gloversville, NY
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Thanks for the thoughts guys. Especially the part about the spring tension. That makes sense. I hope the tabs are still "bendable". Bob, you are right about pulling the lower cowl. The PITA factor definitely comes into play. I installed a quick drain on the oil tank just to avoid pulling the lower cowl on oil changes. I think it has been about 60 hours since I last pulled it. More info when I have pulled the muff.
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  #6  
Old 03-20-2013, 06:59 AM
Dave12 Dave12 is offline
 
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Good catch. Looks like those tie wraps held up pretty well!
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Last edited by Dave12 : 03-20-2013 at 07:25 AM.
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  #7  
Old 03-20-2013, 07:00 AM
BigJohn BigJohn is offline
 
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Quote:
Originally Posted by NASA515 View Post
Finished my airplane today - 1 year and 2 days.
Wow, that's great Bob! Fast time, but you have a lot of experience so I imagine that helps. Have fun with the flight testing. John
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RV-12 N37JP 120176 Flying since 2012.
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  #8  
Old 03-20-2013, 09:15 AM
rvbuilder2002 rvbuilder2002 is offline
 
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Location: Hubbard Oregon
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Quote:
Originally Posted by NASA515 View Post
Just wondering of the PITA part of the cowl installation process resulted in less surveillance than would be the case if more easily removable.
In all fairness to the 1000's of people reading your opinion Bob... what aircraft are you comparing the RV-12 too?

Have you ever removed the cowling from a Piper or Cessna or Beachcraft?
I have. Many times.
Some are easier than others. Some are more involved than the RV-12.

And then some... I think were designed just to give certain people something to complain about...
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  #9  
Old 03-20-2013, 10:31 AM
Dave12 Dave12 is offline
 
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Location: Elkton, Md.
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Quote:
Originally Posted by rvbuilder2002 View Post
In all fairness to the 1000's of people reading your opinion Bob... what aircraft are you comparing the RV-12 too?

Have you ever removed the cowling from a Piper or Cessna or Beachcraft?
I have. Many times.
Some are easier than others. Some are more involved than the RV-12.

And then some... I think were designed just to give certain people something to complain about...
I can have my cowling completely off in 10 minutes. I believe that would place the 12 on upper end of the "easy/quick to remove" scale. That includes removing the air damper heat mod.
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  #10  
Old 03-20-2013, 11:04 AM
Hal-san Hal-san is offline
 
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Location: Spanaway, WA
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Getting it off is pretty quick and easy. Getting it back on is where the pain comes into play.
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Last edited by rv6rick : 03-21-2013 at 11:35 PM. Reason: Removed expletive
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