In-flight engine malfunction and air turn-back, 240 km west of Darwin, Northern Territory, on 24 September 2006, VH-TJI, Boeing 737-476

On 24 September 2006, during a scheduled passenger service from Darwin, NT, to Denpasar, Indonesia, the left engine of a Boeing Co 737-400 series aircraft sustained a mechanical failure within the first-stage low-pressure turbine (LPT) section. After reducing the engine thrust to minimise vibration and further damage, the flight crew returned the aircraft to Darwin.

Following an analysis overseen by the Australian Transport Safety Bureau, the engine manufacturer found that it was likely that thermally induced microstructural creep damage had contributed to the blade failure and subsequent damage to the turbine stage. An examination of the engine maintenance and operating records did not reveal any instance/s of hot-starting or significant take-off exhaust-gas temperature exceedance that may have contributed to the premature failure.

A total of seven related LPT stage-one failures had been identified by the engine manufacturer, including two from the subject Australian operator. While work by the engine manufacturer to better understand the issue was continuing, a range of stage-1 LPT blade production batches were identified as possibly being predisposed to premature failure. The engine manufacturer has recommended that LPT blades from the identified batches be removed from service and quarantined at the next maintenance opportunity, pending their further investigation and assessment of the issue.