In-flight engine failure and shut down, 148 km north-north-west of Launceston, Tasmania

Boeing Company 717-200 aircraft, VH-VQB, was operating a scheduled passenger service from Launceston, Tasmania to Melbourne, Victoria when the right (number 2) engine failed during the climb to cruise altitude.  After securing the failed engine, the flight crew declared a PAN condition and continued the flight to Melbourne where the aircraft landed uneventfully.

Examination of the failed BR715-A1-30 engine by the operator’s maintenance staff and subsequently by the engine manufacturer under the supervision of a representative of the German Federal Bureau of Aircraft Accident Investigation (BFU), confirmed a mechanical failure within the engine high-pressure turbine section.  The failure was traced to the fatigue fracture and loss of a single stage-1 high-pressure turbine blade, with the resultant cascading mechanical damage to the downstream turbine elements and the initiation of a high-temperature titanium metal fire within the high-pressure compressor stages.

Characteristics of the failed turbine blade fracture surfaces indicated that a high-cycle (vibratory) loading environment had contributed to the development of the fatigue cracking that led to the blade loss.  A significant contributor to the magnitude of the vibratory blade loading was the extent of trailing edge erosion and metal loss exhibited by the turbine nozzle guide vanes (NGV).  Those vanes progressively degrade in service due to the effects of oxidation and thermal cycling and are typically removed from service once the erosion and damage exceeds serviceable limits.  While not evident during the examination, it was suspected that pre-existing blade mechanical damage may have acted in concert with the vibratory loads to initiate cracking.

Following the investigation, the manufacturer implemented several changes to the maintenance regime for the BR715 engine, including monitoring of the P30 engine parameter that reflects the level of NGV erosion and the mandatory replacement of eroded NGV segments that may otherwise have been repaired and returned to service.