SDR USAA2013012500010

Service difficulty report · Check Valve · Boeing 737401

Difficulty date: January 24, 2013
Submitted: January 25, 2013
Operation: Air carrier
Aircraft: N406US
Make and model: Boeing 737401
Aircraft serial: 23876
Aircraft time: 66,483 hours, 44,684 cycles
System (JASC): 2120 · Air Distribution System
Part: Check Valve
Condition: Failed
Location: Zone 100
Stage of operation: CL
How discovered: O
Nature of condition: O
Precautionary procedure: A

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

CREW REPORTED THE AIRCRAFT WILL NOT HOLD PRESSURIZATION WITH BLEEDS AND PACKS ON IN EITHER STANDBY OR MANUAL WITH OUTFLOW CLOSED. FLIGHT RETURNED TO FIELD AT MIA AND LANDED WITHOUT INCIDENT. MAINTENANCE PRESSURIZED AIRCRAFT AND FOUND AIR GUSHING OUT OF THE CONDITIONED AIR DUCT ATTACHMENT POINT AT THE BOTTOM OF THE FUSELAGE. REMOVED AND REPLACED SWING CHECK VALVE PER AMM 21-21-15. ALSO, REMOVED AND REPLACED A/C DUCT ASSEMBLY DEBRIS SCREEN PER AMM 21-21-12. OPS AND LEAK CHECK GOOD PER AMM 21-00-05.