Qantas B744 near San Francisco on Aug 31st 2010, uncontained engine failure

Last Update: April 16, 2012 / 13:12:59 GMT/Zulu time

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Incident Facts

Date of incident
Aug 31, 2010

Airline
Qantas

Aircraft Registration
VH-VYA

Aircraft Type
Boeing 747-400

ICAO Type Designator
B744

The Australian Transportation Safety Board (ATSB) released their final report concluding the probable causes were: Contributing safety factors - High service time stage-2 LP turbine blades were susceptible to a reduction in fatigue endurance as a result of vibratory stresses sustained during operation at speeds close to the maximum. [minor safety issue] - It was likely that as a result of the reduced fatigue endurance limit, a single stage-2 LP turbine blade fractured and separated from the LP disc during engine operation. - LP turbine support bearings (part numbers LK30313 and UL29651) showed increased susceptibility to breakdown and collapse under vibratory stress conditions associated with LP turbine blade release. [minor safety issue] - It was likely that vibratory stresses from the LP turbine blade loss resulted in the LP turbine support bearing collapse, allowing contact between the LP and IP turbine shafts. - The IP turbine shaft severed as a result of contact between the IP and LP turbine shafts, which ultimately resulted in the uncontained failure event. Other key findings - Cockpit voice recorder audio of the engine failure event was not available to the investigation, as it had been overwritten as a result of the time elapsed during aircraft return and ground operations subsequent to the event. The engine manufacturer and the ATSB agreed in their analysis of the sequence of events that the fracture and release of a stage 2 low pressure turbine blade resulted in secondary fractures and releases of turbine blades. The imbalance as result of these releases overloaded the low pressure turbine roller bearing and caused it to fail, the low pressure turbine shaft began to orbit and made contact with and eventually severed the intermediate pressure (IP) turbine shaft. The fracture of the IP turbine shaft permitted the IP turbine disc to overspeed losing its axial and radial position, the disc and blades contacting adjacent engine components and the blades being released from the disc. The released blades entangled with the stage 1 low pressure turbine nozzle guide vanes and caused the engine casing to rupture and release of debris. The engine manufacturer released two non-modification service bulletins as result of the occurrence recommending to use more robust LP turbine bearings at the next maintenance visit, at the time of the release of the final report 68% of the engines in use world wide had already been accordingly modified. High service stage 2 turbine blades are recommended to be replaced.
Aircraft Registration Data
Registration mark
VH-VYA
Country of Registration
Australia
Date of Registration
Nebbbfmniiili Subscribe to unlock
Airworthyness Category
Pjlhjmgkcdmkjceqmp Subscribe to unlock
TCDS Ident. No.
FAfbh Subscribe to unlock
Manufacturer
THE BOEING COMPANY
Aircraft Model / Type
737-838
ICAO Aircraft Type
B738
Year of Manufacture
deg Subscribe to unlock
Serial Number
Cnngn Subscribe to unlock
Maximum Take off Mass (MTOM) [kg]
Mqpki Subscribe to unlock
Engine Count
I Subscribe to unlock
Engine
QgpjilmfhqhjhbAgbgmlnnnfmmAlpbni dkmliigbpgp Subscribe to unlock
Main Owner
Kqjlqgkkpm pmkgjfAmknjj iemmhdeqmhqmpqmphcnbfdpqbimbdmiAmediAhkqfeg djjmjqqfi Subscribe to unlock
Main Operator
JkncdphbffehdAjepcqckAhqhpelAkqgAfipicenilAlhhmgefeefdkibpAd q hfcmkibAidelm c Subscribe to unlock
Incident Facts

Date of incident
Aug 31, 2010

Airline
Qantas

Aircraft Registration
VH-VYA

Aircraft Type
Boeing 747-400

ICAO Type Designator
B744

This article is published under license from Avherald.com. © of text by Avherald.com.
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