oceanplexian Posted January 29 Report Share Posted January 29 2007 CTSW I take the cowling off every other flight so it this must have happened recently. Muffler has developed a decent sized crack. Looking for opinions, could it be welded or replace it? I found this kit and am wondering what else would be needed https://www.leadingedgeairfoils.com/catalog/product/view/id/3437/s/exhaust-assort-stainless-steel/category/3164/ ? Thanks! Quote Link to comment Share on other sites More sharing options...
gisurvey Posted January 29 Report Share Posted January 29 Hi Oceanplexian, 2008 CTLS, the same issue after 800h. Welding. Quote Link to comment Share on other sites More sharing options...
Roger Lee Posted January 29 Report Share Posted January 29 It can be welded. I've seen several CT mufflers welded and haven't had any issues since. Quote Link to comment Share on other sites More sharing options...
procharger Posted January 29 Report Share Posted January 29 I had a 2 inch hole blow out in mine years ago had it welded no problem. Quote Link to comment Share on other sites More sharing options...
Anticept Posted January 29 Report Share Posted January 29 The rotax installation manual states what stainless steel material these are. Make sure that if you have them welded, the proper alloys are used. Stainless is much more sensitive than regular steel to welding alloys used. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted January 29 Report Share Posted January 29 At 800 hrs you are not buying much time and the risk of CO is not worth it. This muffler metal is fatigued far beyond the crack. Also when the crack is welded a lot of impurities get into the weld from inside. This is an issue when using TIG or any other method. Also not sure what type stainless these mufflers are made of. I doubt they are 321 stainless which is the only way to go for longevity. Don't waste your time chasing a worn out muffler, my muffler started cracking at 700 hours. I temporarily welded the cracks until I found a permanent solution. I ended up with a custom identical muffler out of 321 stainless along with new pipes at half the FD cost, but I am ELSA. The only difference between FD muffler and stock rotax muffler are the ring spacers for the heat muff, and they charge an extra $1000 for it, RIDICULOUS rip off. No legitimate repair facility I know would ever repair cracks in mufflers today by just welding it, way too much liability and contaminated welds. When I worked as an A&P in the 70's for a Piper dealer I was required to oxycetalene weld cracks in mufflers. That would never happen today. Quote Link to comment Share on other sites More sharing options...
oceanplexian Posted January 29 Author Report Share Posted January 29 Thanks for all of the input, my plane is actually at 1300 hrs, I'm not even upset if this is how long a muffler should be able to last. But if welding it can buy me a few months until I have to drop $$$$ on a complete new system that would be helpful. I run a CO meter in the cabin and don't use the heat, moved to a warmer climate last year. Quote Link to comment Share on other sites More sharing options...
Anticept Posted January 29 Report Share Posted January 29 The area in question is in fact 321, and any welder worth their salt will be opening this thing up to clean the backside aggressively. This is not something that should go to any welder, it should go to a shop that deals with exhaust repair. Quote Link to comment Share on other sites More sharing options...
oceanplexian Posted January 29 Author Report Share Posted January 29 Also, it sounds like the stock rotax muffler doesn't have the mounting points for the heater shroud? If so that's unfortunate. Quote Link to comment Share on other sites More sharing options...
Anticept Posted January 29 Report Share Posted January 29 It does not. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted January 29 Report Share Posted January 29 2 hours ago, Anticept said: The area in question is in fact 321, and any welder worth their salt will be opening this thing up to clean the backside aggressively. This is not something that should go to any welder, it should go to a shop that deals with exhaust repair. You would have to cut the muffler in half, probably the flame cone is also cracked because it is attached to the same area. Then you would have to clean and reweld. And you would still have 1300 hr piece of junk. Not worth it. Aircraft muffler shops use a small part of the original and make a new muffler, which complies with faa repair requirements. I have all the exact same welding equipment the aircraft exhaust shops have and wouldn't even entertain repairing this muffler. Most certified mufflers are well worn out at 1300 hrs. Quote Link to comment Share on other sites More sharing options...
Anticept Posted January 30 Report Share Posted January 30 We've got a muffler with around 4000 hours now with a similar crack that was repaired as you described and still going strong, and several others with various fixups. You're not wrong in that exhaust repair is FINICKY, but it's not impossible nor may it necessarily be worn out... the welds on these exhausts aren't the best and usually its the welds that crack first and are the origin of these... so it makes me wonder if they're annealing them properly. 321 *needs* proper annealing. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted January 30 Report Share Posted January 30 14 minutes ago, Anticept said: We've got a muffler with around 4000 hours now with a similar crack that was repaired as you described and still going strong, and several others with various fixups. You're not wrong in that exhaust repair is FINICKY, but it's not impossible nor may it necessarily be worn out... the welds on these exhausts aren't the best and usually its the welds that crack first and are the origin of these... so it makes me wonder if they're annealing them properly. 321 *needs* proper annealing. That is completely incorrect. When welding 321 exhaust you use 316 filler rod and there is no annealing whatsoever. Someone is giving you bad info and they don't know what they are talking about. As for a 4000 hr exhaust I have never seen anything close to this on any aircraft in 50 years. Quote Link to comment Share on other sites More sharing options...
Anticept Posted January 30 Report Share Posted January 30 ?????????????????????? You use 347, not 316. 316 filler is not in any chart that I have for 321 period. 321 does need annealing after forming. 347 in certain circumstances but I'm not positive if welding is one. That's part of the "wondering". As for the 4k exhaust: That's a you issue then. We've had to do several cup replacements, and the side did crack (not as badly as what the threat poster showed), but it never cracked again on the side. I can't comment on standard aircraft exhausts though I know they do love to work through near the exhaust valves after seeing piles of those at a shop I visited while still in school. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted January 30 Report Share Posted January 30 Welding and rewelding mufflers is counterproductive. Exhaust system wall thickness becomes less over time which leads to more failures. It wasn't long ago that someone came within minutes of dying in a CT ( no exaggeration) because of a defective exhaust. But that's another story for another time for someone else to tell if they want to. I can assure you 316 is used for 321 for aircraft exhaust not 321. Just like you don't weld 4130 steel tubing fuselages with 4130 filler rod. So when you go to a local welder in town and you tell him what filler to use or he uses a filler that may not be compatible with your guess on type of stainless then problems show up later. Cheap is not the way to maintaining aircraft but I see a lot of it everyday just outside my hangar. I have been doing this a long time and have seen many get injured or die needlessly. If you want to weld 321 exhaust like I do talk to aircraft exhaust welding shops for advice. I can assure you that it is much much harder that you realize especially on pipes. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted January 30 Report Share Posted January 30 This is what real quality 321 pipe welding looks like. There are not many that can do this. I may never be able to do this in my lifetime but will try. Quote Link to comment Share on other sites More sharing options...
Anticept Posted January 30 Report Share Posted January 30 I don't know why 316 is being used in exhausts as filler for 321. It goes against all the material I have. The one single thing it has going for it is its ease of weldability, but 347 is superior for exhaust because of the heat resistance and the prevention of precipitating chromium carbides at intergranular boundaries at elevated temperatures leading to corrosion and cracking with cycles. 316 is quite vulnerable to this problem and is worsened by welding especially if it's not annealed. Maybe 347 is newer than 316 and everyone's stuck with 316 out of tradition. I'm not sure. The industry has problems with being stuck with long outdated methods too, be it because of the relatively niche application, or that it's geriatrics are working on 50 year old knowledge and haven't learned anything new, or the wheels of regulation turn at the same rate. Maybe you are misremembering. Maybe there is something I'm missing. Maybe 316 is that much CHEAPER to work with and nobody expects it to be a problem within the lifetime of the part. Maybe 316 is much happier to work with leaded fuels. But I am missing something if 316 is the standard and nobody's asked about moving to 347. It's like how material recommends copper antisieze on stainless parts. Mountains and mountains of evidence and research that say it will corrode the stainless and NICKEL should be used and other industries and standards have caught up with that, but AVIATION material still says copper. As for the exhausts, I've lost count of the amount of repairs we have done. We had the one crack on the side, but the rest of the time, it's replacing the cups from wear. These exhausts last quite a long, long time. I imagine the lead creates a lot more problems in a standard aircraft exhausts with the lead, but I don't know if the lead oxide can react with the stainless like elemental lead can. Elemental lead corrodes stainless badly. Your experiences are just not matching up to mine, despite tens of thousands of hours of service combined in the fleet. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted January 31 Report Share Posted January 31 My suggestion to you is talk to the people that have been doing this for 50 years plus. I will take their advice over yours. The people I have dealt with for years made the exhaust system for the only B29 flying among others. I think they know what they are doing, maybe you should call them to let them know they are doing everything wrong. I'm sure they would appreciate your vast knowledge in aircraft exhaust repair. This is one of the most absurd conversations I have ever had on this forum. Quote Link to comment Share on other sites More sharing options...
FlyingMonkey Posted January 31 Report Share Posted January 31 Madhatter, did your CT exhausts ever make it into production? They looked beautiful. Quote Link to comment Share on other sites More sharing options...
GlennM Posted January 31 Report Share Posted January 31 Why is this so hard? The American Welding Society lays everything out. Quote Link to comment Share on other sites More sharing options...
Anticept Posted January 31 Report Share Posted January 31 8 hours ago, GlennM said: Why is this so hard? The American Welding Society lays everything out. Quote Link to comment Share on other sites More sharing options...
Madhatter Posted January 31 Report Share Posted January 31 UNBELIEVABLE Quote Link to comment Share on other sites More sharing options...
Madhatter Posted January 31 Report Share Posted January 31 10 hours ago, FlyingMonkey said: Madhatter, did your CT exhausts ever make it into production? They looked beautiful. This exhaust is a copy of the original but much higher quality however it can only be used on ELSA and is available. This is the problem with SLSA as the manufacturer controls all parts and can charge whatever they want. Quote Link to comment Share on other sites More sharing options...
GlennM Posted January 31 Report Share Posted January 31 9 hours ago, Madhatter said: UNBELIEVABLE I know! It is crazy how someone wrote all this down so people could reference the latest knowledge. I like this better than relying on someone's memory. Could this be a reason you see so many cracked exhausts? Quote Link to comment Share on other sites More sharing options...
Madhatter Posted January 31 Report Share Posted January 31 22 minutes ago, GlennM said: I know! It is crazy how someone wrote all this down so people could reference the latest knowledge. I like this better than relying on someone's memory. Could this be a reason you see so many cracked exhausts? The reason you see so many cracked exhaust components is that the aircraft are getting older with more hours. This is not rocket science, it's been occurring since the Wright Brothers. It amazes me that people are so cheap that they make every excuse possible to salvage junk. You do not see this in certified anymore, that went out the door many years ago, I was there. The one thing saving people from CO incidents in CT's is there is a lot of outside airflow at the upper cabin. People have a $100,000 plus aircraft and are too cheap to replace the exhaust system when required. When someone has an accident due to CO the person who approves the repair or did not inspect the exhaust will be hung out to dry by the lawyers. That's why you don't see this issue in certfied anymore, no one will touch it. Quote Link to comment Share on other sites More sharing options...
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