Muffler Issues

[ravenboy]

This is my first question...

Has there been reports of early failure of Raven, or Raven II muffler due to exterme heat that resulted in a crack apprearing and a small balloon forming on the muffler. It looks like the exterme heat also broke the metal and now becomes impossible to weld.

Only a 2 year old heli, with less then 600 hours....

Any light will be appreciated.

[booster]

This is my first question...

Has there been reports of early failure of Raven, or Raven II muffler due to exterme heat that resulted in a crack apprearing and a small balloon forming on the muffler. It looks like the exterme heat also broke the metal and now becomes impossible to weld.

Only a 2 year old heli, with less then 600 hours....

Any light will be appreciated.

 

Ive seen it bubble and crack by the bubble but it wasn't from heat. Backfiring was the cause in the few ive seen. Guys doing mag drops to long

[Ollie]

I've seen one badly cracked exhaust on a Raven II, as if the material had some defect. I've never seen an exhaust so damaged, even on turbocharged airplanes. The 44 has about 600 hours.

 

[RTR]

I think it is unlikely caused by heat. More than likely caused from repeated backfires during start. Back fires can be caused by a few things, mag timing, improper staring procedures etc etc.

 

Have to replace a muffler on a RavenII for this exact reason now as well. Funny, I don't ever`recall having this problem with the straight Raven or Astro's before.

 

Now here is a question for those having starting problems with RavenII's. Have you complied with RHC R44 SB-55?

 

I suspect that those in compliance with this SB are having fewer starting issues (at least this has been my experience), and easier starting means no backfires and longer muffler life.

 

Just a thought and my humble $0.02 worth.

 

cheers,

RTR

[Ollie]

All the birds I have access too have had this SB completed.

[booster]

How is the engine running at idle? And at higher RPMs. If the machine runs really good you may have to look at what i said in my before posting

[ravenboy]

How is the engine running at idle? And at higher RPMs. If the machine runs really good you may have to look at what i said in my before posting

 

It runs just fine at idle, no specific problem at starting it, maybe I flooded it once or twice when hot, more difficult then, no back fire to speak off.

Although I am a private pilot, it is maintained according to commercial standard, and all SB, including the 55 and the recent change of a part from that SB, have been done,

 

just changed the throttle bearing as well....

 

seems the Robinson has more replacement ahead of scheduled ones.

 

also, my AME just inspected another R II today and the muffler started a few bubble on it, which might lead to a few cracks...

 

Thanks all for the feedback, I just fired an e-mail to Robinson, curious to read their response....maybe they'll just repeat that the warranty is expired, out of luck!

[Ollie]

We just changed a muffler on a Clipper II with 309 hours on the clock. Cracked at the left side exhaust and just about to where the pipe carries the gases out from the heating sleeve.

 

[FUDNUF]

I have been around R44s for 10 years and have replaced a few exhaust systems.

You can expect to replace your muffler and collectors around the 500 hr mark.

R44 Astro, Raven, Raven II.

The Raven II seems to run hotter so it tends to burn out mufflers quicker.

Acorn Welding has a jig to repair the mufflers.

RHC is not willing to increase the thickness of the metal to make the exhaust system last longer.

Best advice is to inspect your exhaust system as required and make sure you CO detector is working, try and keep the backfires to a minimum, it's hard on exhaust systems and Magnetos.

RHC warrenty 1000 hrs 2 years

My two cents

 

FUDNUF