As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WOULD NOT PRESSURIZE. FOUND PRESSURIZATION CHECK VALVES MISSING. FOUND MISSING CHECK VALVES JAMMED INSIDE OF PN 50-380053-1 VENTURI. REMOVED CHECK VALVES, INSTALLED SERVICEABLE PRESSURIZATION VALVE ASSY, PN 1302-2. SYSTEM OPS CHECK SATISFACTORY. SUGGEST A POSSIBLE 10-YEAR LIFE LIMIT ON THIS STYLE VALVE ASSEMBLY.