Questions about pitting in the camshaft

[Diamondsare4ever]

Context:
- 2005 DA40 recently purchased
- Engine TT: 400 (TBO: 1600-2000)
- Air Frame TT: 580
- Plane was hangared its entire life.
- As part of the pre buy inspection an oil analysis was performed and metals were detected, but very minimal, about what you’d expect for a plane that is not flown often. A&P stated that once flown more consistently the next oil analysis should come back cleaner.
- unrelated party mention the risk of cam shaft pitting and recommended an inspection due to the low time on the engine.
- After purchasing and flying the plane back (about 13 hours of flight time), plane flew beautifully and no noticeable issues were noted on the engine instruments or by how the plane flew.

Questions:
- Would you still consider doing an engine teardown to perform a borescope review of camshafts for pitting (my understanding is that cost is aproximen 30k)? Or is this a little excessive / out of the ordinary for a new plane purchase?
- Is there another way to determine if the camshafts have pitting or damage?

New plane owner, so thanks in advance for any insight you share!

[Rich]

The way Lycomings are built examining the cam/followers requires cylinder removal at the least to get access. There won'y be any outward indications of this wear problem until it's extremely advanced.

I've been through this. Inactivity is the culprit and this engine has seen plenty. I would do a couple of oil changes, maybe 10 hours apart. It goes away or it gets worse. In my case two successive oil changes showed it worsening. The engine was pulled and essentially IRAN'd. The steel flakes had caused scoring and some valve damage in one cylinder. The bill for the repair was $15K in 2015.

[Charles]

I had a full overhaul done last year for $37k USD including engine removal and installation and genuine Lycoming cylinders. If you're going to spend $30k on that repair, you might as well do a full overhaul which in theory is due after 12 years anyway.

Short of a full teardown, removing one cylinder would allow you to have a look at part of the camshaft to get a sample of its overall health. Sample procedure: https://www.youtube.com/watch?v=b8aUDb0EMCQ

[Rich]

You will have to remove multiple cylinders to inspect all six camshaft lobes. In my case it was only two of the six lobes. Some pictures after teardown:

[Diamondsare4ever]

The way Lycomings are built examining the cam/followers requires cylinder removal at the least to get access. There won'y be any outward indications of this wear problem until it's extremely advanced.

I've been through this. Inactivity is the culprit and this engine has seen plenty. I would do a couple of oil changes, maybe 10 hours apart. It goes away or it gets worse. In my case two successive oil changes showed it worsening. The engine was pulled and essentially IRAN'd. The steel flakes had caused scoring and some valve damage in one cylinder. The bill for the repair was $15K in 2015.

Not sure if folks are saying to be concerned or more providing insight into what it would take to confirm if there is pitting?

Rich, it seems like your saying to fly it for about 30-50 hours with oil changes and analysis every 10 hours to see if the amount of metals detected are increasing or decreasing, is that correct?

[Rich]

The way Lycomings are built examining the cam/followers requires cylinder removal at the least to get access. There won'y be any outward indications of this wear problem until it's extremely advanced.

I've been through this. Inactivity is the culprit and this engine has seen plenty. I would do a couple of oil changes, maybe 10 hours apart. It goes away or it gets worse. In my case two successive oil changes showed it worsening. The engine was pulled and essentially IRAN'd. The steel flakes had caused scoring and some valve damage in one cylinder. The bill for the repair was $15K in 2015.

Not sure if folks are saying to be concerned or more providing insight into what it would take to confirm if there is pitting?

Rich, it seems like your saying to fly it for about 30-50 hours with oil changes and analysis every 10 hours to see if the amount of metals detected are increasing or decreasing, is that correct?

Not necessarily that many hours. I would fly it 5-10 hours after the previous oil change and change it again, checking the filter. Then maybe one more 5-10 hours and again change the oil and examine the filter. If there are still steel shards in the filter it's a matter of how many versus the previous. Not putting at least a few hours between changes might not be enough to capture enough particles to be meaningful. Flying too many hours before addressing the problem (if there is one) risks doing more collateral damage from the metal shards.

BTW if you go with a factory overhaul I'm told they will modify this model engine to have roller tappets.

[Diamondsare4ever]

The way Lycomings are built examining the cam/followers requires cylinder removal at the least to get access. There won'y be any outward indications of this wear problem until it's extremely advanced.

I've been through this. Inactivity is the culprit and this engine has seen plenty. I would do a couple of oil changes, maybe 10 hours apart. It goes away or it gets worse. In my case two successive oil changes showed it worsening. The engine was pulled and essentially IRAN'd. The steel flakes had caused scoring and some valve damage in one cylinder. The bill for the repair was $15K in 2015.

Not sure if folks are saying to be concerned or more providing insight into what it would take to confirm if there is pitting?

Rich, it seems like your saying to fly it for about 30-50 hours with oil changes and analysis every 10 hours to see if the amount of metals detected are increasing or decreasing, is that correct?

Not necessarily that many hours. I would fly it 5-10 hours after the previous oil change and change it again, checking the filter. Then maybe one more 5-10 hours and again change the oil and examine the filter. If there are still steel shards in the filter it's a matter of how many versus the previous. Not putting at least a few hours between changes might not be enough to capture enough particles to be meaningful. Flying too many hours before addressing the problem (if there is one) risks doing more collateral damage from the metal shards.

BTW if you go with a factory overhaul I'm told they will modify this model engine to have roller tappets.

What would that mean? roller tappets? Is that a good or bad thing?

[Rich]

Roller tappets are supposed to be an improvement. I think they are now standard on Lycomings. Instead of the tappets and lobes sliding across each other they roll.

[MarkA]

Another option you might want to consider for a second expert opinion is to sign up for one https://www.savvyaviation.com/savvybasics/ support services.

My experience is that they're really knowledgably working through these types of issues and for a few hundred dollars it may be worth it to gain access to their experience.

[Rich]

Information on Lycoming tappets:
https://www.lycoming.com/parts/tappets
https://www.lycoming.com/sites/default/ ... ifters.pdf
I determined my engine was serviced with the newer hyperbolic part 15B26262. I don't know whether it had older design tappets or not.

The shop (Premier in Troutdale, OR) put an amazingly complete record of the work they did right in the engine log, including applicable service instructions and AD compliance.