What was found
IN THE COURSE OF TROUBLESHOOTING A PRESSURIZATION DEFECT, REF SDR 20151216018 ELECTRO-PNEUMATIC OUTFLOW VALVE 2095F030800 WAS INSTALLED. THE ACFT WAS RELEASED PENDING SATISFACTORY TEST FLIGHT WHICH SUBSEQUENTLY FAILED YIELDING DIFFERENTIAL PRESSURE RESULTS OF APPROXIMATELY 5.1 MAX DIFFERENTIAL. THE ELECTRO-PNEUMATIC OUTFLOW VALVE, PN 2095F030800 WAS THEN REPLACED AGAIN. THE ACFT WAS RELEASED PENDING SATISFACTORY TEST FLIGHT WHICH SUBSEQUENTLY PASSED YIELDING A MAX DIFFERENTIAL PRESSURE OF 6.0 PSI. THE SUBJECT ELECTRO-PNEUMATIC OUTFLOW VALVE, SN176, WAS TESTED FOR VALVE OVERPRESSURE RELIEF IAW JIC 21-31-00, FUT 10,000 AND FAILED TO RELIEF AT THE PRESCRIBED PRESSURE, VALVE OPENED EARLY.