ALSO, the Wayalla issue would NOT have avoided disaster had it been run full rich. There was a crank issue as well. The engines were NOT run lean. THEY WERE NOT RUN LEAN. They were run "not rich enough" ROP. If one does not grasp the significance of that, one is lacking in the understanding necessary to evaluate the event properly
This was always the problem with flying Pa31s (or any other GA aircraft), every operator did things differently, how they arrived at their procedures probably came from different types and rumour rather than good condition monitoring and trend maintenance.
I guess I am looking for something in an AFM that says, look at the EGT, lean until peak, then continue leaning until 50 (or whatever) cooler. Are there any examples of this?
There is a procedure in the PA-31-350 manual para 4.37 "lean side of peak" procedure.
(a) set desired power setting and lean until peak;
Do not exceed 1650F EGT
(b) if peak is below 1650F or less continue to lean until maximum of 50F reduction in EGT. Readjust manifold pressure to desired setting.
(c) (long winded procedure for use if 1650F is achieved prior to peak)....
It does not state when to use this, or what fuel flow will be achieved.
In smaller pipers such as the Warrior and Arrow it states to lean (power settings below 75% only) until rough then enrich only enough to allow smooth operation, if the engine is able to run smooth LOP it will be LOP.