Service difficulty report · Blades · Boeing 747422

Difficulty date
October 6, 2004
Submitted
October 12, 2004
Operation
Air carrier
Aircraft
N180UA
Make and model
Boeing 747422
Aircraft serial
25224
Aircraft time
57,652 hours, 7,191 cycles
Engine
Pwa PW4056
Part
Blades
Condition
Failed
Location
Nr 3 Engine
Stage of operation
CR
How discovered
O
Nature of condition
Y, J
Precautionary procedure
J, A

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

What was found

LOSS OF NR 3 ENGINE. DECLARED EMERGENCY AND DUMPED FUEL. LOSS OF ALL OIL QUANTITY AND NO N1 INDICATION. T1 BLADES BROKEN. IN-FLIGHT SHUTDOWN OF THE #3 ENGINE WAS DUE TO THE FRACTURE OF SEVEN T-1 BLADES THAT CAUSED AN INBALANCE TO THE ENGINE CREATING MASSIVE SECONDARY DAMAGE TO THE ENGINE. THE CAUSE OF THE T-1 BLADE FRACTURE HAS BEEN DETERMINED TO BE THREE HPT DUCT STOPS LIBERATING LOSE FROM THE TURBINE NOZZLE. THESE STOPS ARE HELD IN PLACE BY BOLTS IN THE TURBINE NOZZLE MODULE. ROOT CAUSE OF THE IFSD HAS BEEN DETERMINED TO BE IMPROPER TORQUE OF THE BOLTS THAT RETAIN THE DUCT STOPS AND DUCT SEGMENTS. THE CORRECTIVE ACTION WAS TO REMOVE ENGINE FROM SERVICE AND OVERHAULED TO THE RING CASE CONFIGURATION.