The following are a set of articles by Bill Marvel, past president of the American Yankee Association, and Bill Scott, an independent overhauler. Note that the opinions expressed here do not necessarily reflect my (Gregory Travis) opinions.

Bill Scott has recently filed suit against Textron Lycoming regarding their Service Bulletin 505. Service Bulletin 505 deals with corrosion in hollow crankshaft Lycoming engines.

• A general overview of the exhaust valve wear issue

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• Service Instruction 1479 and You
• S.I. 1479 -- Round 2
• An open letter to TBO Advisor subscribers
• Hydraulic lifters 101 and the rest of the [TBO] story...
• Clearing up some confusion
• O-320H Cam spalling - suicide?

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• A rebuttal to all this by a reader of the Australian AOPA magazine
• And a reply to the rebuttal by Bill Marvel and Bill Scott

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• Oil measurement test protocol

We solicited rebuttals from both Kas Thomas and Lycoming Engineering. Unfortunately, both declined to comment on these matters.