Powerplant/propulsion event - Launceston Aerodrome, Tasmania, on 20 August 2009

At approximately 1137 EST on 20 August 2009, a Boeing 737-8BK aircraft, registered VH-VOC, departed Launceston, Tasmania on a scheduled passenger service to Sydney, New South Wales. Following take-off, several loud bangs were heard from the left engine, consistent with a compressor surge. The left engine was reduced to flight idle and the aircraft returned to land at Launceston.

The compressor surge and damage to the left engine was the result of advanced variable stator vane bushing/shroud wear, which caused a seal retainer to dislodge from the inner shroud segment and move into the compressor gas path. The liberated seal segments then progressed downstream, causing significant impact damage to the remaining stages, resulting in a loss of compressor efficiency.

The manufacturer was aware of the propensity for inner bushing wear, and had previously released a number of service bulletins aimed at eliminating the issue.

The operator had incorporated the relevant service bulletins into their inspection and maintenance program as required; however the event occurred prior to the engine reaching the earliest threshold for inspection.