On 10 November 2009 at around 1900 EST, a Boeing Company 737-467 aircraft, registered VH-TJY, departed Brisbane Airport, Queensland for Melbourne, Victoria. As the aircraft was climbing through 24,000 ft, the flight crew observed abnormal indications associated with the right engine. The aircraft was returned to Brisbane where it landed without further incident.
Engine disassembly and inspection revealed significant damage to the stage-1 low-pressure turbine (LPT). Analysis of the stage-1 LPT blades showed that some blades had sustained levels of thermally-induced microstructural degradation, which may have affected the creep resistance of the alloy and resulted in the blades being susceptible to failure by creep rupture.
Creep rupture was identified as the likely failure mechanism in previous stage-1 LPT blade failures in this engine type investigated by the Australian Transport Safety Bureau and the engine manufacturer. As a result of this occurrence and at the time of writing this report, the engine manufacturer is revising service bulletin SB 72-1113 to expand the range of blade manufacturing batch numbers that had previously been identified as being predisposed to creep-related failure. Blades in the identified batches are to be withdrawn from service as soon as they are next removed from the engine.
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Material characteristics of some the LPT blades installed in engine 858322 were consistent with a raw material manufacturing cast that had previously been identified as being susceptible to creep rupture
|Who it affects:||Operators of aircraft fitted with CFM56 engines|
|Date:||10 November 2009||Investigation status:||Completed|
|Time:||1930 EST||Investigation level:||Complex - click for an explanation of investigation levels|
|Location:||120 km SW of Brisbane Airport|
|State:||Queensland||Occurrence type:||Abnormal engine indications|
|Release date:||20 July 2011||Occurrence class:||Technical|
|Report status:||Final||Occurrence category:||Incident|
|Highest injury level:||None|
|Aircraft manufacturer||The Boeing Company|
|Type of operation||Air Transport High Capacity|
|Damage to aircraft||Minor|
|Departure point||Brisbane, Qld|