IO540,

I still assume that most pilots have some respect for the engines. A magneto timing that's too far advanced will give very high CHT's even if the pilot is doing everything by the book.

A few years ago an Australian Navajo lost both engines at night over the sea. Fingers were pointed at the pilot's leaning practices. Luckily there were paper records of the engine parameters at every flight as required. Careful examination of these data pointed to improperly set magneto timing on a new engine. In order to fit the engine in the Navajo nacelle, the magnetos must be canted for installation, they were only retimed after about 100 hours of high CHT operation, by then the cylinders were heat damaged.

A proper monitoring system would have caught these errors on the first flight before any damage was done an lives lost.