Check those mufflers

[Tom Baker]

I'm doing a rubber replacement, and I always check the mufflers. I found one today with two leaks, both which would have went directly into the heat muff. I have 4 plugs that are made from https://www.aircraftspruce.com/catalog/eppages/pushrodseals.php and a bolt, nut, and two washers. You can tighten the nut to tighten the plug in the hole. To connect to the tailpipe I use https://www.aircraftspruce.com/catalog/eppages/intakehoses_08-03700.php coupled to my shop-vac blowing air. Use what ever connection works best for your shop-vac. I just used what I had laying around. Spray soapy solution and watch for bubbles.

[Tom Baker]

[FlyingMonkey]

I had to have a hairline crack welded on mine last year.

[Madhatter]

I have been warning about that for years. FD has a defect in welding their muffler heat muff stand-off rings which causes cracks in the muffler. I suspect that most CT's have cracks over 800 hrs. The only thing saving people from CO issues is the large amount of air leaks in the cockpit. There is no difference between LSA and certified when it comes to this. It is a huge issue in certified with a lot of AD'S. Most good shops (good for Tom) pressure check mufflers at annual now, it's a huge liability issue for them. 

[Anticept]

We're discovering them rather often too.

 

Please remember to fill out service difficulty reports.

[procharger]

i Had about 3 inch hole blow out in mine couple years ago never heard

any difference in sound it warped the cowl a little bit from heat. happened

at around 1500 HRS

Edited November 27, 2022 by procharger
miss spell word

[Madhatter]

Almost all aircraft get about 1000 hrs or less when problems start. Be ready for sticker shock from FD. If you buy from Rotax you still have to weld the heat muff rings on. You can only patch mufflers for so long,  if the flame cone fails you can lose power when it blocks the exhaust pipe. There are a lot of airworthiness directives on these issues.

[Animosity2k]

Are all the areas prone to cracking visible with the cowling on or do I need to remove it and check all the way back to the headers?

[GrassStripFlyBoy]

Hey Mike - not visible, and even with it off and the shroud is removed, it requires a shop vac to pressurize the muffler and soapy water to expose possible cracks.  Servicing exhaust is not hard just takes a bit of time, and the proper materials like stainless anti seize for joints, maybe bending the spring tabs back if things are loose, some new springs are wise too.  If you're concerned about it, CO detectors are fairly cheap too.

 

[BravoFoxtrot]

I believe the plugs required are about 1-1/4". Could anyone confirm this? Thanks

[Tom Baker]

1 hour ago, BravoFoxtrot said:

I believe the plugs required are about 1-1/4". Could anyone confirm this? Thanks

That sounds about right. I showed what I use in the first post. It was parts that I had just laying around, but they are not terribly expensive to buy. The one muffler I had come back from repair looked like they had used duct tape to seal it off.

[BravoFoxtrot]

Ok, thanks!