M-5-235 exhaust

[pitts10ch]

Hey guys,

I just took my exhaust off with intentions of sending it to Dawley for overhaul. The left muffler has a broken flame tube and the bottom was actually sagging (melted) and was ready to let go. This would have been nasty had it not been caught. Does anybody have any other ideas about exhaust solutions/ issues that work for the long haul. Apparently Dawley has a deal that they do that makes the exhaust much more reliable. We'll see. Thanks.

Chris

[maules.com]

Dawley, Knisley, and Atlee Dodge among others all rebuild mufflers if there is some part of the OEM muffler to work from. Price is about the same as new from Maule and in some cases , better.
Pressure inspections are needed to find just what you did.
If the throttle is reduced too quickly, it causes backfire which sounds like mild popping to the pilot who is flying away from it, however those sounds are explosions of reburnt gasses forced back up the tailpipe which meet the other exhaust trying to get out.
A wrongly mounted tailpipe will also cause major damage by breaking away the rear of the can. The tailpipe should be supported by its flexible hanger at the firewall and be loose enough at the can, not to rattle too bad but to be moved at the end of the pipe 2+inches in all directions.
If these rules are adhered to the Maule mufflers will make 900hrs.
Keep an eye on the joint clamp locater dowel which is addressed by a service requirement.
The heat shields will last much longer if a couple turns of safety wire are pulled around them at midpoint to stop rattle which developes from differential expansion of stainless and aluminium, or a hose clamp will do but not too tight.

[robw]

Does the same apply to an M4 with the Franklin 220 exhaust, i.e., should the tailpipe be relatively loose?

[maules.com]

The tailpipe weight should be carried at the firewall so that it does not put twisting down action on the back of the muffler. The engine rotates in its mounts and the mufflers are attached to the engine so there should be freedom of movement at the tailpipe joint. On the Franklin, the support at the rear of the right muffler is prone to fatigue.