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If someone recommends something different than the POH, ask them to provide approved data to allow you to operate the aircraft using their method.
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This from Lycoming?????
"allow you to operate..." That's ridiculous. The POH "allows you to operate" anywhere you choose, unless it's in the LIMITATIONS section. The rest is nothing more than a "recommendation."
No one on the face of this earth has offered more hard data to pilots, mechanics, and OEM representatives than the teachers at Advanced Pilot Seminars. "Approved data?" What the heck is that? Because the FAA has stamped it as "approved" has nothing to do with it's scientific validity.
Over a decade ago, I asked Lycoming to provide data to back up some of their statements. I'm still waiting. Nada, Nunca, NOTHING. Why would someone not show their supporting data--unless they don't have any. Some of Lycoming's recommendations don't even agree with their own published data. Go figure?