Posted for "Tom Gourley" <res18fcm@verizon.net>:

I'm certainly no expert on this subject, but I seem to recall an article that also said the prop driving the engine is not a good thing.  I believe the explanation was that when this happens the pressure in the crankcase will be higher than the pressure in the combustion chambers of the cylinders -- something that does not happen under normal operation of an aircraft engine.  (Car engines do this all the time but are designed for it.)  If I'm remembering the article correctly, in some cases this has been known to induce ring flutter, which apparently is not good.  As for de-tuning, I'm not sure what the A&P was referring to.

Tom Gourley
tom.gourley@verizon.net
L2K #122
Banks, OR