What was found
DURING TEST FLIGHT, BOTH PRESSURE RELIEF VALVES DID NOT OPEN AT 9.5 PSID. REPLACED BOTH PRESSURE RELIEF VALVES, OP CHECKED OK ON GROUND REF AMM.
- Difficulty date
- November 30, 2011
- Submitted
- December 5, 2011
- Operation
- Air carrier
- Aircraft
- N174UA
- Make and model
- Boeing 747422
- Aircraft serial
- 24381
- Aircraft time
- 85,083 hours, 9,544 cycles
- Engine
- Pwa PW4056
- System (JASC)
- 2133 · Pressure Regulator/Outflow Valve
- Part
- Outflow Valve
- Part number
- 7159953
- Part serial
- 150156
- Condition
- Malfunctioned
- Location
- Cabin Pressure
- Stage of operation
- CR
- How discovered
- C
- Nature of condition
- L
- Precautionary procedure
- O
As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.