Service difficulty report · Shutoff Valve · Boeing 747451

Difficulty date
February 14, 2012
Submitted
February 16, 2012
Operation
Air carrier
Aircraft
N105UA
Make and model
Boeing 747451
Aircraft serial
26473
Aircraft time
72,437 hours, 8,594 cycles
Engine
Pwa PW4056
Part
Shutoff Valve
Part number
79299910
Part serial
9812049
Condition
Faulty
Location
Bleed System
Stage of operation
CL
How discovered
O
Nature of condition
J
Precautionary procedure
O

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

What was found

RIGHT WING BLEED OVERHEAT, FLIGHT DIVERTED. NR 3 ENGINE BLEED DOES NOT INDICATE OFF ON SYNOPTIC PAGE WITH ALL FOUR ENGINES RUNNING AND NR 3 ENGINE BLEED SWITCH IN OFF POSITION. CMC MESSAGE 36272 BLEED 3 PRSOV SOLENOID FAILED OPEN. CYCLED SWITCH, AND ADVANCED THROTTLE, NO HELP. WITH NR 3 & NR 4 BLEED SWITCH OFF AND ISOLATION VALVE CLOSED, RIGHT WING DUCT PRESSURE INDICATES ZERO, BUT NR 3 BLEED VALVE SYNOPTIC IS AMBER AND IN TRANSIT. REPLACED NR 3 PRSOV PER MM. LEAK CHECKED OKAY.