Service difficulty report · Relief Valve · Boeing 747422

Difficulty date
July 18, 2006
Submitted
July 21, 2006
Operation
Air carrier
Aircraft
N177UA
Make and model
Boeing 747422
Aircraft serial
24384
Aircraft time
67,557 hours, 8,508 cycles
Engine
Pwa PW4056
Part
Relief Valve
Condition
Stuck
Location
R4 Door Slide
Stage of operation
IN
How discovered
V
Nature of condition
O
Precautionary procedure
K

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

What was found

DURING OPERATIONAL CHECK OF DOOR 4R POWER ACTUATING SYSTEM AND ESCAPE SLIDE, NR 2 PILLAR DID NOT FULLY INFLATE AND PRESSURE RELIEF VALVE ON RT SIDE STUCK OPEN. ACCOMPLISHED QUALITY ASURANCE OPERATIONAL CHECK OF DOOR 4R POWER ACTUATING SYSTEM AND ESCAPE SLIDE. NR 2 PILLAR DID NOT INFLATE FULLY & PRESSURE RELIEF VALVE (PRV) ON RH SIDE STUCK OPEN AS REPORTED. PRV WAS IMPROPERLY CALIBRATED. NORMAL MIN IS 2.3 PSIG AND MAC IS 2.8 PSIG. STUCK OPEN EXCEEDED MIN VALUE. ALSO, THE SLIDE SHEAR PIN ON NR 2 PILLAR FAILED TO SEPARATE WHICH PREVENTED FULL INFLATION OF THE PILLAR. SUSPECT TIME-IN-CONTACT CAUSED ADHESION OF SLIDE PARTS.