The Engine Comes off Again

[PT20J]

On 5/24/2024 at 5:39 PM, gevertex said:

Is that a crack in the baffle (bottom right of the baffle, lower left of the picture)?

[gevertex]

18 hours ago, PT20J said:

Is that a crack in the baffle (bottom right of the baffle, lower left of the picture)?

I can't tell from the photo. But if it is a crack, it appears to be stop-drilled. The engine is coming off for an IRAN shortly, so all of that is going to get looked at.

[bhtitle]

My cylinders were replaced ~200 hours ago before I bought my plane, by a mechanic I haven’t otherwise worked with. Aside from that mechanic’s signature as legal proof they were installed correctly, is having my mechanic re-torque the studs to spec an acceptable way of checking that I don’t have the same issue? Or does that not work considering the description earlier of how the studs are loaded?

Also, are there other known physical indications? I’ll for sure keep an eye on EGTs, but stuff like excess oil leaking out the studs or from the seams between cylinders and case.

[redbaron1982]

9 hours ago, bhtitle said:

 

My cylinders were replaced ~200 hours ago before I bought my plane, by a mechanic I haven’t otherwise worked with. Aside from that mechanic’s signature as legal proof they were installed correctly, is having my mechanic re-torque the studs to spec an acceptable way of checking that I don’t have the same issue? Or does that not work considering the description earlier of how the studs are loaded?

Also, are there other known physical indications? I’ll for sure keep an eye on EGTs, but stuff like excess oil leaking out the studs or from the seams between cylinders and case.

I'm 99% sure that you cannot re-torque the studs once installed. To begin with, the torque you apply when tightening a bolt has two "sources": the resistance of the bolt to turn and the tension of the stud. For this studs, what you want is your torque to be coming from the tension of the stud, as that is what causes the pre-load that will keep the cylinder in place.

A stud that has been installed 200 hours ago most likely if you try to re-torque it, most of the torque you apply will go towards overcoming the resistance of the bolt to turn.

I would bet that a properly torqued stud, 200 hours after will most likely require a much higher torque to further tight it.

[EricJ]

11 hours ago, bhtitle said:

 

My cylinders were replaced ~200 hours ago before I bought my plane, by a mechanic I haven’t otherwise worked with. Aside from that mechanic’s signature as legal proof they were installed correctly, is having my mechanic re-torque the studs to spec an acceptable way of checking that I don’t have the same issue? Or does that not work considering the description earlier of how the studs are loaded?

Also, are there other known physical indications? I’ll for sure keep an eye on EGTs, but stuff like excess oil leaking out the studs or from the seams between cylinders and case.

Was there torque-seal paint strips put on the nuts?    This is often done to give a visual indicator if the nut moves at all.    If it was done on your motor, and the torque seal either isn't broken or still lines up, then it's likely fine.

[N201MKTurbo]

You can retorque all the through bolts and studs, but it is a huge amount of work. You need to remove the intake and exhaust and all the pushrods and most of the baffling. There is a service bulletin about the proper way to do it. 
 

Considering what shops are charging these days, you are probably talking a few thousand dollars to do it.

I wouldn’t bother.

[redbaron1982]

9 minutes ago, N201MKTurbo said:

You can retorque all the through bolts and studs, but it is a huge amount of work. You need to remove the intake and exhaust and all the pushrods and most of the baffling. There is a service bulletin about the proper way to do it. 
 

Considering what shops are charging these days, you are probably talking a few thousand dollars to do it.

I wouldn’t bother.

Are you referring to 1029D? That SI covers two scenarios: completely disassembled engine and replacing one cylinder, which means retorquing the free-thru studs, but doesn't specify a procedure to re-torque an already installed cylinder.

[N201MKTurbo]

3 hours ago, redbaron1982 said:

Are you referring to 1029D? That SI covers two scenarios: completely disassembled engine and replacing one cylinder, which means retorquing the free-thru studs, but doesn't specify a procedure to re-torque an already installed cylinder.

You would use the procedure for the whole engine. In most cases, you will set your wrench and pull on it and it will click before the nut moves.

[gevertex]

On 6/9/2024 at 9:30 PM, bhtitle said:

 

My cylinders were replaced ~200 hours ago before I bought my plane, by a mechanic I haven’t otherwise worked with. Aside from that mechanic’s signature as legal proof they were installed correctly, is having my mechanic re-torque the studs to spec an acceptable way of checking that I don’t have the same issue? Or does that not work considering the description earlier of how the studs are loaded?

Also, are there other known physical indications? I’ll for sure keep an eye on EGTs, but stuff like excess oil leaking out the studs or from the seams between cylinders and case.

In my case there was not any oil leaking. If it’s been 200 hours I wonder if that eliminates that as a potential problem for you. 5/8 failed on mine within 87hours tach. 

[PT20J]

21 hours ago, N201MKTurbo said:

You would use the procedure for the whole engine. In most cases, you will set your wrench and pull on it and it will click before the nut moves.

Rich, to get an accurate torque, would it be best to loosen everything and start over? 

[N201MKTurbo]

3 hours ago, PT20J said:

Rich, to get an accurate torque, would it be best to loosen everything and start over? 

I would’t suggest that. Once the cases are clamped up, I wouldn’t unclamp them unless you needed to. If the nuts are tight, I wouldn’t mess with them. Wouldn’t the only reason to retorque be because you suspect something is loose?

[PT20J]

38 minutes ago, N201MKTurbo said:

I would’t suggest that. Once the cases are clamped up, I wouldn’t unclamp them unless you needed to. If the nuts are tight, I wouldn’t mess with them. Wouldn’t the only reason to retorque be because you suspect something is loose?

I see your point. I don’t think just checking that the wrench clicks before the nut moves means the torque is correct because the breakaway torque is going to be higher than the running torque, but I guess it would uncover anything that was grossly under torqued. 

I guess if it were mine I might consult with Lycoming about the best course of action. 

[EricJ]

Torque plates exist so that clamping pressure can be maintained on the case if multiple cylinders must be removed, since it's generally considered bad to release pressure on the case unless it is being completely disassembled.   

[PT20J]

1 hour ago, EricJ said:

Torque plates exist so that clamping pressure can be maintained on the case if multiple cylinders must be removed, since it's generally considered bad to release pressure on the case unless it is being completely disassembled.   

Yes, but the torque plates are for use if the cylinders are going to be left off for a while. Obviously you have to undue all the fasteners to remove the cylinders and install the plates. So, if torque is in question, why not loosen everything and proceed as if you were installing all new cylinders? The through studs will only be loose for a few minutes. 

[201Steve]

Who last assembled the engine and/or the cylinder? Just curious…

[201Steve]

On 5/24/2024 at 12:22 PM, gevertex said:

Currently prepping to get the engine sent off for an IRAN.

I'm avoiding placing blame about this until the engine is torn down and inspected. Lots of factors here.

OH NOOOOO. I remember you now, we had a discussion about your engine drinking a bunch of oil and I recognized the symptoms and knew exactly where it had come from.

 

Do not kid yourself. This is 1000000% the result of the dumpster garbage work of Jewell Aviation Kennett MO. There's no avoiding blame. There's nothing left to be considered after remembering your scenario. It is just yet another example of many that they have no idea what they are doing and with each new piece of evidence, just pisses me off more and more.  I applaud your patience and hesitancy to place blame. It is normally a quality trait, one that I practice and one that I did practice waiting over a year before I posted my PIREP on them. But GD enough is enough. After reading my experience, us talking about it here on this very forum, you should not feel bad whatsoever about being extremely pissed off that these inbred @$$ clowns could have damn near had you killed. I've said it over and over. I'm not just an unhappy customer. I'm a concerned citizen over the value of life and the utter lack of disregard these people have for it.

It is disgusting beyond measure. I cannot emphasis this enough. Just purely disgusted by this newest revelation.

[EricJ]

1 hour ago, PT20J said:

Yes, but the torque plates are for use if the cylinders are going to be left off for a while. Obviously you have to undue all the fasteners to remove the cylinders and install the plates. So, if torque is in question, why not loosen everything and proceed as if you were installing all new cylinders? The through studs will only be loose for a few minutes. 

My understanding is that generally you shouldn't remove additional cylinders until some clamping pressure is assured with application of torque plates.   In other words, pull off a cylinder or pair of cylinders on the same through bolts, install plate(s), pull the next cylinder, install a plate, etc.  Paying attention to which through-bolts are affected matters, obviously.  Removing all the cylinders or relaxing all of the through-bolts and then installing plates allows the case to relax and potentially unload bearing seating and whatever other Bad Things happen when the case halves relax, so my understanding is that the torque plates are used to help prevent that.

SI1029D describes this a bit for the case for a disassembled engine and torque plates are used to apply initial torque for assembling the case.    The rear torque plates are then removed, the rear cylinders installed and initially torqued, then the next forward torque plates are removed and the cylinders installed, etc.   In other words, clamping pressure is never fully relaxed on the case during the assembly process of cylinder installation.

The overhaul manual isn't as clear on this, but does indicate that the cases are assembled with torque plates for application of initial torque for full assembly of the case halves prior to installation of the cylinders.

The full-assembly first case for SI1029D says it's for when all cylinders have been removed, so it is a little confusing.

I can't find an OM or SI or SB that says so, but my understanding has always been that not doing this (i.e., maintaining clamping pressure on the case halves with the through-bolts) can result in some misalignment or movement of the main bearings that increases the risk of a spun bearing or other bearing failure after subsequent reassembly.   So I'd consider removing torque on all of the through-bolts at the same time to be risky.  

[201Steve]

I am sorry Gevertex, I truly do not mean to hijack your thread, and I certainly do not intend to drag you into my feud or insinuate in any way you did anything wrong, but the whole context needs to be documented here. Anyone that can be warned is a potential life saved, not everyone is going to be as precise as you who sensed something as small as a 50 degree EGT change to then discover an almost departed cylinder. VERY impressive that you caught this before it blew off 200' over the trees.

The whole story starts right here and it was a ticking time bomb right out of their shop.

 

 

[gevertex]

On 6/11/2024 at 7:29 PM, 201Steve said:

I am sorry Gevertex, I truly do not mean to hijack your thread, and I certainly do not intend to drag you into my feud or insinuate in any way you did anything wrong, but the whole context needs to be documented here. Anyone that can be warned is a potential life saved, not everyone is going to be as precise as you who sensed something as small as a 50 degree EGT change to then discover an almost departed cylinder. VERY impressive that you caught this before it blew off 200' over the trees.

The whole story starts right here and it was a ticking time bomb right out of their shop.

 

Thanks, no problem. Some of us who were impacted need to get together and take some action. Collectively, we probably have a very strong case. Really blown away someone hasn't died from these guys yet (they may have). There were two catastrophic failures pending on this engine. Luckily I caught it and got it IRANed to new tolerances. I'll post about that in a minute.

[gevertex]

Engine is complete and looking very good. Extensive work was required to get me back in good shape. Engine was IRANed to new tolerances.

A few items that were reworked/replaced:

• New case
• Overhauled crankshaft/counterweights
• New(to me) first run overhauled cylinder assemblies (including new pistons, etc)
• New #3 connecting rod
• New through-bolts
• New paint job

Hopefully can get her reinstalled in the next couple weeks.

 

This engine is like the ship of theseus at this point. There are very few original components remaining. Maybe only the accessory case is original.

 

[gevertex]

Some of you may be wondering what lead to the problems I had. Root cause was identified as excess paint applied to the cylinder flange causing stud failure. I am told putting paint on the cylinder flange near the mounting holes is a huge no-no. These are supposed to be spot faced.

https://www.aero-news.net/index.cfm?do=main.textpost&id=676BF248-5697-4319-801A-905F7388929C

In addition, the shop found the crank case had significant fretting, missing studs, and over-stressed through bolts. The shop believed the fretting was severe enough to have been present prior to the overhaul done by Jewell.

Lastly, the cylinders I was sold were not overhauled very well. They had significant corrosion on the exhaust studs and clearly hadn't had much or any rework done on them. Certainly not what I expected when I paid for them... There were a handful of other issues as well, but these were minor in comparison.

[EricJ]

Paint on the flange will do it.    Can you say who did the previous overhaul?

[M20F]

12 minutes ago, EricJ said:

Paint on the flange will do it.    Can you say who did the previous overhaul?

Earl Scheib 

[gevertex]

18 minutes ago, EricJ said:

Paint on the flange will do it.    Can you say who did the previous overhaul?

Jewell Aviation in Kennet, MO. Not to be confused with the other Jewell who as I understand it does good work.

[N201MKTurbo]

I spent the night in Kennet MO. In ‘22. It is very strange. There was a giant electric motor plant there. Everybody worked there. The plant closed and there is no reason to live there anymore. The town looks nice, the roads are nice there are nice shopping centers, but all the stores are empty. The town is like a ghost town.