csarles Posted February 24, 2015 Report Share Posted February 24, 2015 Anyone have any ideas what would have caused this crack? I am having it sent out to be fixed. Any advice on where to have it done? Thanks, Curt Quote Link to comment Share on other sites More sharing options...
Awful_Charlie Posted February 24, 2015 Report Share Posted February 24, 2015 The Lycoming exhaust is a bit of a weak point unfortunately - take it to a knowledgeable aviation welder and get the crack area welded and reinforced with gussets. IIRC it is where the #1 header joins to the #3 and #5pipe, and where #2 joins to the crossflow and to #4 joints are the worst Quote Link to comment Share on other sites More sharing options...
N601RX Posted February 24, 2015 Report Share Posted February 24, 2015 Stress, frozen slip joints and vibration are some of the more common causes Quote Link to comment Share on other sites More sharing options...
cbarry Posted February 24, 2015 Report Share Posted February 24, 2015 Outside of the already mentioned possibilities, I'm curious about the interesting placement of the dent just outside of the weld? 1 Quote Link to comment Share on other sites More sharing options...
N601RX Posted February 24, 2015 Report Share Posted February 24, 2015 One thing to keep in mind is that an aircraft engine is mostly aluminum and expands and contracts a lot. If you look at the engine you will see that lycoming has made allowances for this. Intake tubes are mounted rigid at one end, and have some sort of slip joint or rubber coupling at the other Baffling is made in overlapping pieces Pushrod tubes are spring loaded Oil return tubes have rubber joint at one end The exhaust must be able to expand and contract also. If the slip joints don't slip then it gets flexed back and fourth a little each time until it cracks. 3 Quote Link to comment Share on other sites More sharing options...
mooniac15u Posted February 24, 2015 Report Share Posted February 24, 2015 Anyone have any ideas what would have caused this crack? I am having it sent out to be fixed. Any advice on where to have it done? Thanks, Curt Just had mine done by Dawley Aviation in Wisconsin. Very reasonable price and quick turnaround. Http://www.dawleyaviation.com 2 Quote Link to comment Share on other sites More sharing options...
Hank Posted February 24, 2015 Report Share Posted February 24, 2015 Such a little bitty crack . . . Best fix it while it's small. You won't like the price of a replacement. Quote Link to comment Share on other sites More sharing options...
Yetti Posted February 24, 2015 Report Share Posted February 24, 2015 Since it broke along the weld. Bad weld. Too much heat while welding. Vibration just finished the job. Quote Link to comment Share on other sites More sharing options...
FoxMike Posted February 24, 2015 Report Share Posted February 24, 2015 The Bravo exhaust is grim. I have owed two other turboed airplanes have had little problems with their exhaust systems. I would suggest you send the whole system to a good welding shop so they can do it right. When you get it back lube it well before you reinstall it. Keep an eye on the TIT during high power. I have found keeping the TIT around 1600F will help you get max life out of the system. I have found that using 30/2200 about 75% will keep the TIT around 1600F at peak. Good Luck! 1 Quote Link to comment Share on other sites More sharing options...
Cruiser Posted February 24, 2015 Report Share Posted February 24, 2015 actually the weld strength is greater than the surrounding metal from the looks of it. There is too much stress there and this causes the stress relief to follow the path of least resistance. Quote Link to comment Share on other sites More sharing options...
carusoam Posted February 24, 2015 Report Share Posted February 24, 2015 The dent stands out as 'odd' from an engineering point of view... Whatever made the dent, may have loaded up the stress down the pipe. Exhaust system continuity is more important for Bravo owners than most Mooneys. Are you familiar with Bravo exhaust clamps? Best regards, -a- Quote Link to comment Share on other sites More sharing options...
hnorber Posted February 24, 2015 Report Share Posted February 24, 2015 Just had mine done by Dawley Aviation in Wisconsin. Very reasonable price and quick turnaround. Http://www.dawleyaviation.com I had an exhaust pipe welded by Dawley a few years ago for an 82 Warrior. They were a short drive from my mechanic in East Troy, WI, and did a fantastic job. They were very quick as well. 1 Quote Link to comment Share on other sites More sharing options...
aviatoreb Posted February 24, 2015 Report Share Posted February 24, 2015 Me too friends...just got the phone call from my mechanic - airplane is in annual. I have an exhaust crack that needs welding. Well, they wouldn't call it an airplane if it didn't need to be maintained. Quote Link to comment Share on other sites More sharing options...
Danb Posted February 24, 2015 Report Share Posted February 24, 2015 I had a similar crack also in my Bravo if your lucky I can be welded..my plane only had 350 hours at that time... Quote Link to comment Share on other sites More sharing options...
csarles Posted February 25, 2015 Author Report Share Posted February 25, 2015 Thanks for all the advice and ideas. Yes, through reading on this site I am aware of the "killer" clamps. We are going to be replacing those as well, just to be sure. I too am curious about the dent and the fact that unless it is recent (after the last annual), not one mechanic ever pointed it out to me. Lesson learned: be more involved in the annual. Funny thing, if you look at it and let your eyes cross a little, it almost looks like an older Mooney logo. Curt Quote Link to comment Share on other sites More sharing options...
jetdriven Posted February 25, 2015 Report Share Posted February 25, 2015 Those clamps are 1200$ each I heard Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted February 25, 2015 Report Share Posted February 25, 2015 FWIW I have found a good way to assemble exhaust slip joints. The secret is to get the mating surfaces clean enough so they slip freely together without undue force. I do this by sanding them till they are almost shiny. They usually have a thick costing of exhaust residue and it takes aggressive sanding to get it all off. Before assembling coat both mating surfaces with spark plug anti seize. It will act as a grease when you are putting the system together allowing all the pipes to find there happy place and the pipes will slide properly as the engine heats and cools, which most don't. And next time you take it apart it will come right apart. The first time I took the exhaust system apart on this plane I had to wedge one piece in the trailer hitch of my truck and put a 10 foot pipe in the other piece to get the slip joint apart. Now I just need to give it a couple of twists and it comes apart. Quote Link to comment Share on other sites More sharing options...
jetdriven Posted February 25, 2015 Report Share Posted February 25, 2015 The permatex silver goo antisieze or that champion spark plug stuff which looks like liquid graphite. Quote Link to comment Share on other sites More sharing options...
csarles Posted February 25, 2015 Author Report Share Posted February 25, 2015 Yikes! Although one could rationalize that it's cheaper than a life. Supposing for a moment that I don't want to replace them, what is the best way to find out if they need to be replaced? According to the log books the plane has never had them replaced. There also was a prop strike in 1996, before I owned it, and they were not replaced at that time either. Quote Link to comment Share on other sites More sharing options...
carusoam Posted February 25, 2015 Report Share Posted February 25, 2015 I'm pretty sure there is a maintenance procedure to follow on that, regarding number of times they can be torqued. Having the exhaust system come apart is bad in two ways... Excess heat, lack of power.... Go MooneySpace, -a- Quote Link to comment Share on other sites More sharing options...
Tony Armour Posted February 25, 2015 Report Share Posted February 25, 2015 Everytime I change the oil, 25 hours, I spray Mouse Milk on all the joints and wastegate. BTW, it does not necessarily take an aviation shop to weld that but of course you want someone that really knows what they are doing....not the dude next door that built his own lawnmower trailer :-) 1 Quote Link to comment Share on other sites More sharing options...
LANCECASPER Posted January 8, 2016 Report Share Posted January 8, 2016 (edited) A crack was noticed on my exhaust pipe Number 7 on the diagram The crack didn't look so bad on the tailpipe when it was on the engine. But it turns out after it was taken off that it was only being held together by about 30% of the weld. Here's my shiny new tailpipe I don't like to think about what would have happened if that had separated in flight. Edited January 8, 2016 by LANCECASPER Quote Link to comment Share on other sites More sharing options...
Bob_Belville Posted January 8, 2016 Report Share Posted January 8, 2016 I lost a piece of the tailpipe between PDK and MRN a few months after buying my Mooney! We had not noticed any cracks. Upon further examination we found that the guts of the muffler were coming apart. I priced overhaul and decided to go with Powerflow. The Powerflow system calls for disassembly and anti-seize at every annual. System is now almost 4 and looks like new. Quote Link to comment Share on other sites More sharing options...
carusoam Posted January 8, 2016 Report Share Posted January 8, 2016 That is an amazing photo, Lance. The exhaust stains give a hint of how bad the situation is. The results for a similar separation of a the turbo exhaust would even be more serious. Makes me wish it was easier to open the cowl to take a look. The best I can do is tug on the end of the pipe. Having 10% of the weld may make it difficult to notice. How did you notice it? Thanks for sharing those. Best regards, -a- Quote Link to comment Share on other sites More sharing options...
LANCECASPER Posted January 8, 2016 Report Share Posted January 8, 2016 Brian Kendrick noticed it during maintenance. 1 Quote Link to comment Share on other sites More sharing options...
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