What was found
ACFT EXPERIENCED AN IN FLIGHT FAILURE OF THE PROPELLER PITCH CHANGE DIAPHRAGM. THE PILOT PERFORMED AN EMERGENCY DECENT AND A NORMAL LANDING AT THE AIRPARK. UPON SHUTDOWN A TOTAL OF 7 QUARTS OF OIL HAD BEEN LOST. THE DIAPHRAGM HAD BEEN REPLACED 2 YEARS AGO AND HAD LESS THAN 200 HOURS TIME IN SERVICE. ONCE DIAPHRAGM WAS REMOVED, A SMALL TEAR WAS EVIDENT ON THE OUTSIDE CONSISTENT WITH A PRESSURE FAILURE FROM THE INSIDE OUT. LOOKING AT THE INSIDE OF THE DIAPHRAGM REVELED NUMEROUS CRACKS IN THE MATERIAL. PILOT STATED THE ONLY OPERATING CHANGE MADE IN THAT TIME WAS A SWITCH FROM 100 TO 100 PLUS OIL .