Club Homepage Forums Classified Ads Buy & Sell - Everything But Airplanes Tweety turns into a Turkey

Just a buyer beware I guess. Tweety had her first 100hr and I had the mechanic replace one of the pushrod tubes, it had a small ding where someone had slipped a wrench or something. Should have left it alone. He pulled the cylinder to replace it and looked inside the case- why I don't know, mechanics being mechanics I guess. He found some major rust on the camshaft. Small maintenance turns into major teardown. Man. Prebuy had great compressions, logs looked good, factory reman last overhaul even. Clean engine, ran smooth. But I guess it sat somewhere too long with high humidity. Sigh. Big thing to miss. Ouch. Have to cash out the retirement funds to fix this I suppose.

Most every cam shaft I have seen in older engines have rust. As long as it is not major and pitted and not on the cam lobs where the followers are it should not pose a problem. Others may have a different opinion but I put 700 hours on a 49 C170 that had rust but none on the cam lobs.

I'm inclined to agree with Dale!

Surface rust in and of itself is not a problem, as long as it's not on the actual contact surfaces where the followers ride on the cam (very unlikely on a recently operated engine). Any pitting on the contact surfaces (narrow area in the middle of each lobe) is cause for alarm, as this wears the cam followers and eventually the cam lobe itself. "Major rust" on the cam itself between the lobes or bearing journals hurts nothing. I would not disassemble an engine for surface rust alone on interior components that does not interfere with operation, especially since operation has been normal since being placed back into service.

All engines with any time on them that have ever sat for more than a few days have some surface rust on steel parts, somewhere inside them. Doesn't hurt a thing. An engine that has sat for months or years might be a different story!

I guess the decision here would be based on the definiton of "Major Rust" and where on the cam it actually appears, and why your mechanic is overly concerned. He may be right, or just too cautious, or maybe otherwi$e!

I just went through this (although for different reasons). Carl and Dale are right on. The Cam rust issue is if the pitting is sufficient to penetrate the hardened surface of the cam lobe itself. While you need to make your own judgement on the issue, just surface rust is not a reason to declare the part unairworthy.

I just tore down my Lycoming (O-360) because we couldn't find anything else wrong, but the cam was fine after sitting 5 years with little to no activity.

He said major and he is the one that signs me off so I don't have much choice. He told myself and the flight school owner he could not authorize a return to service as it is. So I'm kinda stuck. It has been shipped to Triad in NC as of this afternoon. Basically, if it comes out to 6K or under (not likely), I'll get it repaired and run out the 900hrs left, if not I'll just bite the bullet and do an overhaul. But I need to get it back on the flight line asap. There are a couple of kids that were ready for prep and checkrides and I'm letting them down, I feel bad about that but not much I can do.

If we must err, it's always best to do it on the side of caution! I'm sure it's for the best in the long run!