Mystery Solved

[bnicolette]

Hi fellow MS'ers,

I've had an interesting couple months. It started in September and should be completed in the beginning of November.

We were doing a routine oil change back in September. During the oil change my mechanic pulled the oil screen and it was packed with "sludge" and some metal parts. (see picture) This is the first time that the screen had been pulled since I owned the airplane. (more on that later)

Upon initial inspection of the metal parts my mechanic could not identify what they might have come from. Most perplexing was this ball that was found in the mix. We then cut open the filter and found that it was clean. My mechanic's best guess was that the ball came from the tappet but that didn't make any sense as if the tappet had come apart there is no way the engine would be running properly. Just prior to doing the oil change I had taken the airplane out for a :30 flight to warm up the oil and everything was perfectly normal. We immediately took pictures of the parts and sent them off to Lycoming for their input on what these parts might be and more specifically the "ball". They called shorty after receiving the pictures and said there is no way that these parts came from this engine. They theorized that either the engine had a catastrophic failure somewhere along the way and these parts were never retrieved or somebody used a dirty funnel to pour oil in sometime without knowing these parts were in the funnel. So the quest for an answer continued. I took it upon myself to email the pictures to many top name engine overhaulers to get their input and they came back with the same thing Lycoming did.

One thing was for certain though and that was, I didn't want to fly the airplane anymore until somebody could give us a positive answer or it was torn down and inspected. Lycoming suggested we fly it for another 10 hours and then pull the screen and filter again but that was not an option for me.

[bd32322]

Wow good thing you pulled the engine, finding those in the oil screen would be a serious concern to me.

And really there is almost no way to throw a ball into the engine while filling oil with a funnel it would have rolled out of the funnel as soon as you moved it

[timpercarpio]

Wow, that's just crazy. At our last oil change we found some ferrous metal in the filter. We should get our oil analysis back tomorrow. We changed the filter again after about 14 hours and there was still metal in the filter, just not as much. We sent out for another analysis.

The oil screen was clean. It's been about 800 hours SMOH. If we're facing an overhaul, it's nice to have another shop to consider.

We just bought the plane in March 2012 and it's been running great with no issues until the last oil change. This was the fourth oil change since we bought it.

If we need an overhaul, any suggestions would be appreciated.

[David Mazer]

So, did you misunderstand Lycoming when they said this couldn't have come off the engine and they really meant that it came off of the engine but wasn't really a part of the engine? Or something like that.

[bnicolette]

So, did you misunderstand Lycoming when they said this couldn't have come off the engine and they really meant that it came off of the engine but wasn't really a part of the engine? Or something like that.

Hi David,

No, Lycoming came right out and told me that this part (ball) did not come from this engine. We even mic'd the ball and gave them the dimensions and they said the only thing it could have come from was the tappet as it is the same size, but also said that it would not be possible for it to come from the tappet and still be running properly.

[bnicolette]

Wow good thing you pulled the engine, finding those in the oil screen would be a serious concern to me.

And really there is almost no way to throw a ball into the engine while filling oil with a funnel it would have rolled out of the funnel as soon as you moved it

Bd32322

I couldn't agree with you more and I guess they were theorizing that there could have possibly been something sticky in the funnel (grease, sealants, etc...????). Didn't make much sense to me but when everybody (not just A/P's or IA's but engine specialists) are telling you that there is no way that this kind of part could come from your engine all sorts of things start coming to mind. Even sabotage was a possibility.

[carusoam]

So, what is supposed to retain the oil nozzle in it's place?

Apparently the ball and spring maintain pressure on the nozzle, what keeps it in it's place?

-a-

[jetdriven]

It threads into the case.

[N601RX]

If I remember correctly from when we reassembled our engine these have a 1/16 NPT thread, the same as a few of the other internal oil plugs. However if you look in the table of limits in the back of the overhaul manual these 4 nozzels have a different torque from the other 1/16 npt plugs. Its likely these were installed with the lower generic torque instead of the higher specific torque for this part.

The ball and spring closes the flow of oil any time the oil pressure drops below about 40psi. Above that it opens up and sprays oil.

I just looked this up to make sure. Lycoming list the generic torque for a 1/16 npt thread as 40in-lbs. These nozzles are also 1/16 NPT, but their torque is specifically listed at 100 in-lbs. That would explain all them being loose. I'm suprised the engine was able to hold 60 psi oil pressure with one of them out. The nozzles get their oil directly from the main bearing galley.

[KSMooniac]

Wow! Nice catch, and thanks for sharing the entire story.

[xftrplt]

Well done, Sherlock.

[bnicolette]

Well done, Sherlock.

Well thank you Mr. xftrplt!! If I only had Watson along with me it could have been determined much earlier!