Engine Question - Metal Making Event. Lycoming O320

[bt3vex]

Brain Trust,

I pulled the sump filter after 70 hours for the first time since Major Overhaul (Me and a A/P friend did the overhaul) and found flat ferrous flakes more than a teaspoon (See Attached Picture). No metal in the oil filter just the sump filter. Sent off to get analyzed and came back as oxidized metal w/ no source. Since the finding I have grounded the plane, but been running the engine to see if its still making metal. After 5 hours pulled the sump and drained the oil, clean as a whistle. Engine runs great, CHTS 350-400, EGT 1350-1375 when running hard.

Options:
1. Pull Jug and inspect Camshaft/Lifters
2. Borescope through oil drain hole and see if I can see anything
3. Borescope jug see if there is anything
4. Go fly - stay close to the airport get 10 hours check again
5. All the above??

Any advice/thoughts from you guys would be greatly appreciated

 

[Girraf]

A borescope in the cylinders is fine but I doubt you'd discover anything interesting from that. I definitely wouldn't pull cylinder just to poke around. I'm not sure how much you can see through the oil drain but probably can't hurt anything to look.

Lycoming has a SB you can reference for guidance. SB No. 480F

https://www.lycoming.com/sites/default/files/attachments/SB480F%2520Oil%2520ServicingMetallic%2520Solids%2520Identification%2520After%2520Oil%2520Servicing%2520and%2520Associated%2520Corrective%2520Action.pdf

I believe their threshold is 1/4 tsp is nothing to get excited about. Since your more than 4x that amount, I might be mildly concerned from a financial standpoint, but not that the engine will fail catastrophically. I think the SB recommends a series of oil changes at progressively larger time intervals, checking for new metal each time.

For example, change the oil, filter, and clean the suction screen and then fly for 5 hours. Change the oil again and look for new contaminants, clean the screen, change the filter and go fly for 10 hrs. Then again for 25 hours. If it keeps coming back clean, then you're probably in good shape. Might have just been some metal from break in that you never found initially?

 

[lr172]

While certainly possible that this metal is post overhaul. What are the chances that cleaning the sump and screen was missed at overhaul and the metal is from the previous event? Oxidized metal particles is not something i would expect to find in a freshly overhauled engine unless it sat for a long time. Coating with assembly lube prevents corrosion for a long time.

Did you flush out the oil galley’s at oh and attack with a bore brush?

 

[bjdecker]

Brain Trust,

I pulled the sump filter after 70 hours for the first time since Major Overhaul (Me and a A/P friend did the overhaul) and found flat ferrous flakes more than a teaspoon (See Attached Picture). No metal in the oil filter just the sump filter. Sent off to get analyzed and came back as oxidized metal w/ no source. Since the finding I have grounded the plane, but been running the engine to see if its still making metal. After 5 hours pulled the sump and drained the oil, clean as a whistle. Engine runs great, CHTS 350-400, EGT 1350-1375 when running hard.

Options:
1. Pull Jug and inspect Camshaft/Lifters
2. Borescope through oil drain hole and see if I can see anything
3. Borescope jug see if there is anything
4. Go fly - stay close to the airport get 10 hours check again
5. All the above??

Any advice/thoughts from you guys would be greatly appreciated

 

[lr172]

While certainly possible that this metal is post overhaul. What are the chances that cleaning the sump and screen was missed at overhaul and the metal is from the previous event? Oxidized metal particles is not something i would expect to find in a freshly overhauled engine unless it sat for a long time. Coating with assembly lube prevents corrosion for a long time.

Did you flush out the oil galley’s at oh and attack with a bore brush?

Should add that it is very rare for an engine making metal to have NONE in the filter. Very suspicious for a currently self destructing engine. There will most always be a combination of particle sizes. You can’t really get large chunks without some of them being ground into smaller chunks, at least not over a meaningful timeframe.

 

[bt3vex]

While certainly possible that this metal is post overhaul. What are the chances that cleaning the sump and screen was missed at overhaul and the metal is from the previous event? Oxidized metal particles is not something i would expect to find in a freshly overhauled engine unless it sat for a long time. Coating with assembly lube prevents corrosion for a long time.

Did you flush out the oil galley’s at oh and attack with a bore brush?

I cleaned the sump super well and put in a new screen at overhaul, but i did not clean the oil gallies or flush them. When I got the engine it had rust on the cam shaft which got replaced along with new lifters, tappets, hydraulic sockets, pistons, rings, bearings, crank shaft gear. It did sit for about a 3 years before I was able to get it running on the plane, but i did coat all parts with appropriate grease just for that purpose. Its possible the metal was from the previous life before I got it.

 

[bt3vex]

Should add that it is very rare for an engine making metal to have NONE in the filter. Very suspicious for a currently self destructing engine. There will most always be a combination of particle sizes. You can’t really get large chunks without some of them being ground into smaller chunks, at least not over a meaningful timeframe.

That's the weird part, the oil itself came back clean from the analysis, the filter was cut open and had a super powerful magnet run all over it (Nothing found), only debris in the sump filter.

 

[BillL]

I would clean all, add fresh oil and go fly for 25 hours and recheck. It is not unusual to collect little bits after an overhaul. You just want to verify that more is not being made, and a teardown is unlikely to find anything at this point.

 

[lr172]

That is a tough one. My gut goes to prior debris, assuming each and every rotating steel part was covered with grease or assembly lube. I just can’t see how a current metal making event can leave a perfectly clean filter. If the block went to divco, I would not think that way, but an amateur can miss various cleaning steps that could account for what you are seeing. Also possible you missed grease on a piece and it broke in large chunks, without creating fine debris. Uncommon but probably possible.

I would probably do what bill suggested, but might make an effort to be very in tune with any slight changes in behavior and limit flights over congested areas.

Imo, a tablespoon full of metal debris is far beyond what is typically found post overhaul, so wouldn’t consider it par for the course. Just one man’s opinion.

Only a call you can make though.