Mooney parts for M20E - Cylinder detachment inflight!

[AM1]

Dear Mooney flyers,

Earlier this year, we had cylinder 3 detach from the crankcase in our Mooney M20E while in the air and were lucky to be near an airport in the UK and land her. Getting to the bottom of what caused this has taken many hours and we are still unable to verify the exact cause of such a significant structural failure. In the meantime, we ordered a new engine (IO 360 A) which is being delivered later this week after a long 4 month wait as Lycoming is running way behind in production.

However, I am writing to seek assistance to find an exhaust part (see below) which was damaged during the incident. I'd be ever so grateful for any steer as to where I could procure the stack pipe cylinder from? Thanks ever so much.

exhaust stack pipe cylinder No 3 Pt No 850-9

 

Edited September 27, 2021 by AM1

[EricJ]

When was that cylinder last removed?    I'm sure you've covered the bases, but my initial thought would be one or more of the fasteners came loose and resulted in a cascade failure of the studs.  There are multiple ways a fastener can come loose.

I cant help with the exhaust part, but it does look like an interesting failure.   Glad the outcome was safe!

[N201MKTurbo]

I have to agree with Eric. From the look of the case, it looks like it has been loose for some time and the cylinder flange was beating on the case. The constant hammering caused the rest of the studs and bolts to eventually fail.

[N201MKTurbo]

It also looks like there might have been sealant under the flange. That is a big no no. The sealant can cause the flange to lose clamping force and allow the fasteners to lose torque.

[Guest]

A new exhaust can be bought from these guys.

https://www.aircraftexhaust.com/nav.cfm?cat=11&subcat=67&subsub=0&as_id=8&mg_id=74&sys_id=121&display=system

Clarence

[carusoam]

Yikes and Welcome aboard AM1!

That is an amazing first post.

Thanks for sharing the pics…

 

Clarence has supplied a great contact for the new exhaust equipment…

There are often people going the OverHaul route… there has been a recent combination of two exhaust suppliers in the US…

 

We have a few MSers in Europe… let me invite @Hyett6420 to stop by… see if he has anything more local to you to add…

PP thoughts only, not a mechanic…

Best regards,

-a-

[Shadrach]

6 hours ago, N201MKTurbo said:

I have to agree with Eric. From the look of the case, it looks like it has been loose for some time and the cylinder flange was beating on the case. The constant hammering caused the rest of the studs and bolts to eventually fail.

How are you distinguishing old scars from hammering over time and the new ones that would resulted after the failure as the detached cylinder bounced off the case, cowl and everything else?  Agree that it looks like there is some sort of sealant on the cylinder flange but that could also be staining from the separation event.

Edited September 28, 2021 by Shadrach

[Guest]

2 hours ago, Hyett6420 said:

Hi AM1.  Welcome aboard to the land of Mooney expertise.   This forum is amazing when it comes to the knowledge that is here.  
 

Re Exhausts we are about to replace our complete exhaust assembly as well (its failed due to age).  We are looking at a powerflow exhaust which is a bit more expensive but has added benefits. 
 

ive pinged you a dm with my mobile number on it.  Give me a call and we can have a chat re options and places to go.  Clarences suggestion is a good one and Clarence is a guy I would trust with my aircraft if I was in the USA. 
 

Andrew

Hi Andrew,

I’d have to emigrate from Canada to the USA! 

Clarence

[N201MKTurbo]

2 hours ago, M20Doc said:

Hi Andrew,

I’d have to emigrate from Canada to the USA! 

Clarence

Just like everybody that lives in Maricopa county lives in Phoenix to people who are not from around here. Everybody in North America lives in the USA to the folks over there.

[N201MKTurbo]

8 hours ago, Shadrach said:

How are you distinguishing old scars from hammering over time and the new ones that would resulted after the failure as the detached cylinder bounced off the case, cowl and everything else?  Agree that it looks like there is some sort of sealant on the cylinder flange but that could also be staining from the separation event.

It just looked like there is some older wear marks, but it is hard to tell from one picture.

[Yetti]

The little ridge at the top of the mating surface on the case.  Then the wear marks on the cylinder around the bolt holes suggest that it has been chattering for awhile.   then dang dude you sheared all your cylinder bolts.

[Shadrach]

36 minutes ago, N201MKTurbo said:

It just looked like there is some older wear marks, but it is hard to tell from one picture.

What are the chances that over torquing could cost something like this? I’m guessing with fasteners that size it would have to be an egregious number

[N201MKTurbo]

20 minutes ago, Shadrach said:

What are the chances that over torquing could cost something like this? I’m guessing with fasteners that size it would have to be an egregious number

I'm not sure. It seems like over torqueing would cause an immediate failure, while under torqueing will allow the nuts to come loose. All the evils the engine manufacturers are always warning about are lack of proper clamping force. Usually by putting unapproved stuff between flanges. 

[Yetti]

The A&P said he wanted to do the final tightening on the hoses....   So I put them all in and he came and did the snug and the extra Umph.  Where you feel it a little in your chest.   I said Oh you wanted them "Tractor tight"  cause that how you tighten the hydraulic hoses on a tractor.

[Shadrach]

5 hours ago, Freemasm said:

Hey Ross. Look at a stress-strain curve. I attempted to attach one copied from the internet below. Said person would basically have to exceed the torque limit twice.  Doubtful but there's always someone that could find a way. I worked with a very talented ex-NAVY nuke. He would always philosophically look my system designs and ask me if they were "Sailor proof". There was no such thing according to him. 

The lab contacts did take a quick look at the photo. Love those guys.  They've helped us here before. His summarized statement is basically:

The picture isn’t enough to be conclusive.  However, the far-right stud fracture (the one raised up with threads showing) is flat and suggestive of fatigue. 

No surprise to me. An over-torque failure/ultimate stress rupture will have some "necking" at the failure point. 

 

Great post! Thank you very much for the insight.

[Shadrach]

5 hours ago, N201MKTurbo said:

I'm not sure. It seems like over torqueing would cause an immediate failure, while under torqueing will allow the nuts to come loose. All the evils the engine manufacturers are always warning about are lack of proper clamping force. Usually by putting unapproved stuff between flanges. 

One can certainly compromise hardware by over torquing without an immediate failure. However, it would take a very strong fool to do it to hardware that beefy.

[Skates97]

Are the exhaust pipes the same on an IO-360 as an O-360? If so I might have what you need at the hangar.

[carusoam]

Way to go Freemasm!

Metallurgist guy…

It is great to have you on the MS team!

Thanks for sharing your insights… again.

Best regards, 

-a-

[A64Pilot]

For some reason Radials are bad about blowing jugs, and it’s not always the bottom ones so it’s unlikely all are due to hydraulic lock. I bring that up as their design is nearly identical, cylinder attachment wise.

I’m not Radial experienced enough to know why they do, I’ve suspected that backfires stress the studs and eventually they break. It’s not all that uncommon.

However if there is high temp silicone under the base of the cylinder, I’d heavily suspect that as a primary cause as with a soft anything between the case and jug it’s loose, even with correctly torqued nuts the soft sealant amounts to movement like a incorrectly torqued cylinder.

In my opinion silicone has no place on an airplane, regular silicone sweats acetic acid as it cures, that’s why it smells like vinegar, and acid is of course corrosive, but where it’s really dangerous is if it’s used in the fuel system, silicone swells up and gets soft, breaks free and clogs your fuel system.

If your determined there is an aircraft type of silicone for installing windows etc that does not sweat acid as it cures.

There are just simply better sealants than regular silicone available, in my opinion

Good thing your replacing the engine as there is no telling about the other three or the rest of the engine as silicone under a jug doesn’t make me confident that a good mechanic was involved.

It’s possible that pre-ignition and or detonation could have been a contributing factor, pretty much anytime something breaks in a engine either could be a factor

https://www.faasafety.gov/files/notices/2019/Jul/Preignition.pdf

Pre-ignition and detonation are different things, with different causes, but the net result is often similar.

Edited September 29, 2021 by A64Pilot

[Guest]

5 hours ago, Hyett6420 said:

Geography was never my strong point

Think of northern colony versus southern colony!

Clarence