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Looking to define the reason(s) exhaust valves fail. reading the LOP thread, there is a lot of generalization about operations - such as damage the engine internal pressure - high ICP burn up your engine detonation there are continual reports of top end replacements at 1000 hours or less, yet some operators can go to TBO without issues. How can we define these differences that make sense relating to exhaust valve failures. Mechanical issues are well documented, alignment and tolerancing is obviously important but it is more than that, even with the mis-alignment it seems some engines survive but others do not. It is certainly linked to operational methods. Let's try to develop specific, measurable factors in operations. Some things that seem important - CHT, EGT, FF, ROP, LOP, POWER, RPM etc.

Good Evening Mooneyspace folks, Discrepancy: Noticed radio static during run-up, after annual completion. Background: "high low volts" problem discovered during night landing 4/10/2013 (discovered 24V landing light installed in 14V system, R & R with PMA LED Landing Light. Replaced voltage regulator, Oil Pressure system and Fuel Pressure system amplifiers, CHT and probe R & R’d….returned to service 5-11-2013 (cost $3500) "high low volts" problem 1/13/2014 (see Annunciator Troubleshooting) Radio Static Repair: After researching Mooneyspace, several forum posts recommended checking master switch first for corrosion. While inspecting for corrosion all “male terminals” on back of switch were clean. However one “female” terminal appeared burnt at locations where previous maintenance had crimped vinyl heat shrink. The wire run appears to go to voltage regulator Notes from attached photos: 1) Burn marks common to crimped locations 2) Discoloration of 0.25” female terminal connection 3) No discoloration of 18 AWG wiring. (0.1 milliohms) 1-27-14, I will install new pre soldered AWG 18 terminal end and heat shrink to R & R wire terminal end. Question: Has anyone else seen burnt wiring and do you know what the root cause was? Thank You Steve