Mooney grounded in Foley, AL

[00-Negative]

Took off for the Bahamas today. During runup I inadvertently left the selector on Left mag and noticed it approx 45 minutes into the flight. My climb rate was awful, but I assumed it was the 98° temp and I was within 20lbs of max gross weight. I changed selector to Both with no noticable change. My remaining cruise seemed slower than normal, but my settings were more economical whereas I usually I fly as fast as possible all the time. At a planned fuel stop at 5R4, I increased throttle while in base leg and suddenly the engine sounded like a car without a muffler. After landing, I pulled cowling and a section of #2 exhaust stack is blown out. Engine is around 500hrs smoh. Recent annual with nothing major. Unsure if exhaust has ever been changed. Plugs have a little carbon, nothing terrible. Question: did my single magneto debacle cause any problems that I should check for? Did it have anything to do with the exhaust stack failure? Side note: during annual, I pointed out a discoloration on the now blown out section of exhaust pipe that I thought was oil residue as we were chasing an oil leak. Maybe it was discolored d/t weakening metal? Anyone have a source on this part? I don't see a miracle happening that will allow us to make it to the Bahamas. 

 

-David

[AIREMATT]

That sucks! Glad you landed safely and it didn’t happen up at cruise.

Cant see how the mag could cause that. Only slightly changes the temps from 2 mags to single mag ops. That must have had a bad spot.

Any idea how the other pipes are? May be worth a look at them while getting this one repaired.

[Shadrach]

Unlikely that the crack happened all on one flight. That pipe looks thin. Might be time for a new exhaust.

[201er]

9 hours ago, 00-Negative said:

Question: did my single magneto debacle cause any problems that I should check for? Did it have anything to do with the exhaust stack failure?

Yes. Flying single mag means there is incomplete combustion which pushes more of the flame front into the exhaust. This causes both hotter exhaust gas temperatures as well as higher pressures.

Didn’t you notice the unusually high EGT and low CHT? How did you lean for cruise? Were you ROP or LOP and how much?

On a single mag, CHTs are lower on all cylinders because there’s less combustion happening in the cylinder. EGTs are higher because the late combustion is happening in the exhaust.

I can’t say whether this destroyed a perfectly good exhaust pipe or just revealed an already failing one. But, I would definitely have them all checked because they were all taking a beating.

[Greg Ellis]

@00-Negative On another thread on Mooneyspace, someone mentioned that planexhaust.com (They said PlaneExhaust.net but that does not seem to exist) was able to make them a down pipe in an hour and get it to them the next day.  Maybe they can do something for you and still help you make it to the Bahamas.  Although with July 4th upon us, that may be difficult.

[BlueSky247]

Gotta be some good ol boy muffler shops around that would be happy to put a patch on there if you can find a way to get that section to them. Assuming the surrounding material is usable. 

[LANCECASPER]

11 hours ago, 00-Negative said:

Took off for the Bahamas today. During runup I inadvertently left the selector on Left mag and noticed it approx 45 minutes into the flight. My climb rate was awful, but I assumed it was the 98° temp and I was within 20lbs of max gross weight. I changed selector to Both with no noticable change. My remaining cruise seemed slower than normal, but my settings were more economical whereas I usually I fly as fast as possible all the time. At a planned fuel stop at 5R4, I increased throttle while in base leg and suddenly the engine sounded like a car without a muffler. After landing, I pulled cowling and a section of #2 exhaust stack is blown out. Engine is around 500hrs smoh. Recent annual with nothing major. Unsure if exhaust has ever been changed. Plugs have a little carbon, nothing terrible. Question: did my single magneto debacle cause any problems that I should check for? Did it have anything to do with the exhaust stack failure? Side note: during annual, I pointed out a discoloration on the now blown out section of exhaust pipe that I thought was oil residue as we were chasing an oil leak. Maybe it was discolored d/t weakening metal? Anyone have a source on this part? I don't see a miracle happening that will allow us to make it to the Bahamas. 

 

-David

I don't think that happened on one flight. Flying as fast as possible, as you mentioned you usually do, means increased heat and that's what takes out exhaust systems eventually over time. If the logs don't say that the exhaust system was overhauled when the engine was you can be reasonably sure it wasn't. If you dig far enough back you should be able to see when it was overhauled. I think a careful examination of the entire exhaust system will show that it's all ready for overhaul.

Your situation is one of many, many reasons I won't be flying a single engine airplane over water for any length of time. Did I do it when I was younger and invincible? Sure. Believe it or not, in 1997 I crossed the Gulf of Mexico beyond glide range to land, without a raft or life jacket. I was at FL250 in a one-year-old Bravo and it was nice to see 300 knots ground speed for much of the flight and it was nice to make it non-stop KSAT-KFXE, but looking back what was my Plan B? I saved some time, but what happens when we have something like that work out it emboldens us to think that it's safe. 

[Utah20Gflyer]

You might check e bay and some other used part sources for that down tube.  

[BlueSky247]

For the sake of discussion, would a powerflow and it's required annual touchy feely have prevented this? Perhaps made of better material?

[PT20J]

Unlikely the single mag operation caused this. Running on a single mag does raise EGT but not enough to destroy a good exhaust system. We have two mags because one can fail and the airplane is designed to continue flight on a single mag.  It sounds like the exhaust was just worn out. It should have been replaced/overhauled when the engine was overhauled but perhaps it wasn’t.

Not sure why going back to both msgs in flight didn’t increase engine performance. That would be worth investigating when you get it back together.

[PaulM]

I once took off in my Bravo on a single mag  (If your run-up is interrupted by something, do the checklist again from the top).  .. and as soon as I leaned for cruise the EGT's shot over redline.  I have no idea how high it would have gone if I didn't reduce MP and figure out what was wrong.   (about 15 seconds after the redline alert) 

This is the G1000 trace for that flight.. the EGTs were in the 1700's and the TIT hit over 1800 .   The bravo has an iconel exhaust which can take 1750.. but will burn it out over time, so I don't normally run it that hot. 

https://apps.savvyaviation.com/flights/shared/flight/3798462/fb5e68da-c7ec-4b5a-83ee-bcd26c41660a

The EGT3 probe is failing, that is why I was flying to the MX shop.

So everyone should check what their plane does, but a max power setting with a single mag is going to be very hard on the exhaust..   

[PT20J]

9 hours ago, PaulM said:

I once took off in my Bravo on a single mag  (If your run-up is interrupted by something, do the checklist again from the top).  .. and as soon as I leaned for cruise the EGT's shot over redline.  I have no idea how high it would have gone if I didn't reduce MP and figure out what was wrong.   (about 15 seconds after the redline alert) 

This is the G1000 trace for that flight.. the EGTs were in the 1700's and the TIT hit over 1800 .   The bravo has an iconel exhaust which can take 1750.. but will burn it out over time, so I don't normally run it that hot. 

https://apps.savvyaviation.com/flights/shared/flight/3798462/fb5e68da-c7ec-4b5a-83ee-bcd26c41660a

The EGT3 probe is failing, that is why I was flying to the MX shop.

So everyone should check what their plane does, but a max power setting with a single mag is going to be very hard on the exhaust..   

Lots of ways to screw up a turbocharged engine. Depending on how high and how long a TIT in excess of redline happens, an inspection of the turbocharger may be warranted. The problem is that these things spin fast and metal grows elastically as the temperature increases and at some point the centrifugal force causes the turbine to drag on the housing trashing things. There are some fairly recent pictures on Beechtalk. 

[00-Negative]

12 hours ago, Greg Ellis said:

@00-Negative

What a long day. Thanks for all of your input. PlaneExhaust has the part in stock for $295 so I had it overnighted to 5R4. With the holiday, it will arrive Friday. I asked the mechanic about a welder and he reluctantly agreed to call a guy that knows a guy. We checked out of our $260/night Hampton Inn and went to the airport where we played Uno for a few hours while waiting. A little after lunchtime the guy showed up with the welded part for $500.. We installed, checked plugs, cylinder compressions, and ground ran without problems. Took off and dodged thunderstorms all the way to Ft Pierce where I'm in a 4 star Hilton resort for $104/night. Money ran fast and flawlessly. First thing in the morning we'll take off for the Bahamas.. Rented a lifeboat just in case.  

-David

[00-Negative]

[BlueSky247]

Glad you got it patched and that welder was available. Have a good trip!

[jetdriven]

Hopefully the welder used the proper filler rod and a Tig with a Lanthanted tungsten. Plus that pipe was cracked almost all the way around. That pipe is 300 series stainless steel, and its mandrel bent around a curve, not commonly available in Foley AL.

Anytthing ca be fixed, theoretically,  but I would replace that part ASAP.

[Hank]

48 minutes ago, jetdriven said:

Hopefully the welder used the proper filler rod and a Tig with a Lanthanted tungsten. Plus that pipe was cracked almost all the way around. That pipe is 300 series stainless steel, and its mandrel bent around a curve, not commonly available in Foley AL.

Anytthing ca be fixed, theoretically,  but I would replace that part ASAP.

Foley is on the outskirts of Mobile. Doesn't Continental build engines there? I wouldn't be surprised that there are people in the area who can rebuild a broken exhaust.

[EricJ]

1 hour ago, Hank said:

Foley is on the outskirts of Mobile. Doesn't Continental build engines there? I wouldn't be surprised that there are people in the area who can rebuild a broken exhaust.

Mobile is actually an aerospace engineering and manufacturing center, so I'd guess it's likely.

[67 m20F chump]

What a great outcome.  I hope you enjoy your vacation!

[Ragsf15e]

13 hours ago, 00-Negative said:

Awesome results, enjoy!

[Shadrach]

On 7/3/2024 at 7:55 AM, 201er said:

Yes. Flying single mag means there is incomplete combustion which pushes more of the flame front into the exhaust. This causes both hotter exhaust gas temperatures as well as higher pressures.

Didn’t you notice the unusually high EGT and low CHT? How did you lean for cruise? Were you ROP or LOP and how much?

On a single mag, CHTs are lower on all cylinders because there’s less combustion happening in the cylinder. EGTs are higher because the late combustion is happening in the exhaust.

I can’t say whether this destroyed a perfectly good exhaust pipe or just revealed an already failing one. But, I would definitely have them all checked because they were all taking a beating.

An aero engine should easily be able sustain flight for long periods of time on a single point of ignition.  The marginally hotter EGT should have little to no effect on the stack.  Even under single mag operation, the EGTs of an 8.7:1CR, IO360 are less than most low compression engines.  There is a possibility that this exhaust was on it's way out and the increased temp hastened its demise, but I think that's unlikely. 

My biggest concern is the condition the rest of the exhaust system. 

[Shadrach]

16 hours ago, 00-Negative said:

Money ran fast and flawlessly. First thing in the morning we'll take off for the Bahamas.. Rented a lifeboat just in case.  

-David

A common characteristic of a general aviation vacation!

[LANCECASPER]

Besides flying over water that far with a suspect exhaust system in a single engine airplane with the family aboard, my second biggest concern would be having another exhaust pipe failure discovered at your destination. While Mobile AL may have a lot of general aviation repair options, the Bahamas don't. 

 

[00-Negative]

On 7/4/2024 at 8:37 AM, jetdriven said:

Hopefully the welder used the proper filler rod and a Tig with a Lanthanted tungsten. Plus that pipe was cracked almost all the way around. That pipe is 300 series stainless steel, and its mandrel bent around a curve, not commonly available in Foley AL.

Anytthing ca be fixed, theoretically,  but I would replace that part ASAP.

Pretty sure the donor metal came from a Piper exhaust stack. The guy that did the job for me is a pilot. He owns a C182. A new down pipe was ordered. I'll plan on replacing the entire exhaust as soon as I get back home. Flight from Ft Pierce was the most uneventful flight we've had. We didn't need to thread the needle between ominous looking thunderstorms. Just boring point A to point B at 7500. Although the flight home in a couple of days looks like dodging thunderstorms all along the gulf coast. 

-David

[jetdriven]

Sounds like it was probably repaired then. It may just be the failure of a slip joint to move because it seized together, this could cause the pipe to crack because the exhaust can’t move around as it heats up. But if you take it all apart and disassemble it and inspect all this, take bodymans hammer and tap on the pipes everywhere and if it goes through the side of it is too thin. But otherwise you can evaluate it and lubricate the heck out of the slip joints. You may not have to buy a whole exhaust, which is a lot.