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SDR 2007UALA01196

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Service difficulty report · Engine · Boeing 747422

FAA SDR system

Difficulty date
April 16, 2007
Submitted
April 20, 2007
Operation
Air carrier
Aircraft
N107UA
Make and model
Boeing 747422
Aircraft serial
26900
Aircraft time
35,352 hours, 4,409 cycles
Engine
Pwa PW4056
Engine time
35,926 hours, 4,912 cycles
System (JASC)
7200 · Engine (Turbine/Turboprop)
Part
Engine
Condition
Shutdown
Location
Nr 1
Stage of operation
CR
How discovered
O
Nature of condition
Y
Precautionary procedure
A

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

What was found

FLIGHT DIVERTED DUE NR 1 ENGINE SHUTDOWN. [06-14-07] TWO BOLTS THAT RETAIN THE OIL PUMP IDLER BEARING (MB-18) OUTER RACE, IN THE MAIN GEARBOX (MGB), HAD BACKED OUT. ONE (1) OF THESE GOT PAST THE MGB SUMP SCREEN, AND INTO THE ROTATING GEAR MESH OF THE MAIN OIL PUMP. THIS CAUSED PUMP SEIZURE AND FAILURE OF THE OIL PUMP DRIVE SHAFT AT ITS DESIGNED SHEAR POINT. THIS WAS A FIRST RUN MGB. IN THE INTERIM UA IS ADDING LOCK LIQUID TO THESE BOLTS, AND IS INSPECTING MGB BEARINGS MB-16, MB-17, AND MB-18 WHENEVER MGB CARBON SEALS ARE REPLACED.