So I am looking into purchasing a plane, and when I spoke with their mechanic, he mentioned that he does not cut the filters at oil changes to check for metal. Besides that fact that it is common practice to do so, is this a reason to run from the plane?

More info:

O-360 on a Cherokee
Its last overhaul was from a reputable shop
It has 800 hours on it.
Overhaul was around 2005
It has been used steadily since then (no long period of disuse)
Borescope of cylinders and comp check came back good

The thing it has going for it in my mind is the constant use, and that it is at the bottom of the "failure tub". The last oil change was only a few hours ago, so cutting the filter now may not tell me too much.

Thanks,

Jesse

While not required during a 100-hour or annual inspection, it seems pretty lazy to me. I cut mine open every oil change, takes 15 minutes and for the amount of diagnostic info you (potentially) get, it is well worth it. While I wouldn't run from the airplane just because of that, I would have it evaluated/pre-buyed by a different mechanic. Agreed cutting a new-ish filter open won't be of much value unless you get lucky. It is a lot like oil analysis, needs to be done consistently to be of much value.

Get an oil analysis done, it's a few bucks and provides peace of mind.

scottf wrote:While not required during a 100-hour or annual inspection, it seems pretty lazy to me. I cut mine open every oil change, takes 15 minutes and for the amount of diagnostic info you (potentially) get, it is well worth it. While I wouldn't run from the airplane just because of that, I would have it evaluated/pre-buyed by a different mechanic. Agreed cutting a new-ish filter open won't be of much value unless you get lucky. It is a lot like oil analysis, needs to be done consistently to be of much value.

There's not a lot that can be done by a pre-buy mechanic to find out how the engine is doing, other than to check compressions, unless the engine has 25-30 hours since the last oil change. Then it would be worth the expense of doing an oil change and filter cut, and pulling spark plugs for examination will tell some stories. You can also run the engine and do a careful run-up. But otherwise, you pretty much have to take an engine apart to find out how healthy it is. Take if from me, even bullet proof O-360s can fail--mine lasted all of 15 hours from the time I left Tulsa until it threw a rod and I landed in a field. So nothing is guaranteed.

But a good pre-buy will often tell you how overall maintenance was accomplished--but again, by your mechanic, not theirs.

Cary

Cary wrote:Take if from me, even bullet proof O-360s can fail--mine lasted all of 15 hours from the time I left Tulsa until it threw a rod and I landed in a field. So nothing is guaranteed.

But a good pre-buy will often tell you how overall maintenance was accomplished--but again, by your mechanic, not theirs.

Cary

Did you do an autopsy on the dead engine? I wonder how often cam spalling and the associated circulation of metal causes catastrophic failure. Both Lycoming and Continental rely on the oil screen to stop metal from circulating. Anything smaller is deemed to be ok to float around in there, making it's way through all the galleries and bearings. How can that be good? Anyway, Continental's cams don't spall often but the engines still fail.

The sort of failure Cary experienced happens too often. Rob had to rebuild just after purchase too. There is just no way to know but I do believe that a full flow oil filter makes sense. I would cut the thing open at every oil change.