On 25 July 2007, a twin engine Cessna 441 (Conquest II) aircraft carrying three passengers was being operated on a scheduled passenger flight from Port Augusta to Adelaide, SA. At 1035 Central Standard Time, while cruising at flight level 210, the aircraft's right engine failed suddenly approximately 23 km north of Ardrossan, SA.
When the failed right Garrett TPE331-8 turboprop engine was removed from the aircraft and subsequently disassembled, it was revealed that the compressor bearing at the front end of the engine had catastrophically failed. That bearing provided both axial and lateral support for the turbine section. Once that support was lost, the engine's rotating turbine section shifted forward under the influence of thrust loads, resulting in rotor-to-case contact and rapid engine failure.
The aircraft had been inspected two months prior to the engine failure for a suspected lightning strike, however the inspection did not reveal any obvious electrical damage at that time. Considerable levels of residual magnetism were found within the compressor bearing and other engine components during the ATSB examination. Such levels indicated that direct electrical current (DC) from an aircraft lightning strike had passed through the engine during service. The passage of such currents resulted in undetected electrical damage and led to the eventual failure of the compressor bearing.
|Date:||25 July 2007||Investigation status:||Completed|
|Time:||1035 CST||Investigation level:||Complex - click for an explanation of investigation levels|
|Location:||23 km NNE Ardrossan|
|State:||South Australia||Occurrence type:||Engine failure or malfunction|
|Release date:||01 April 2009||Occurrence class:||Technical|
|Report status:||Final||Occurrence category:||Incident|
|Highest injury level:||None|
|Aircraft manufacturer||Cessna Aircraft Company|
|Type of operation||Air Transport Low Capacity|
|Damage to aircraft||Nil|
|Departure point||Port Augusta, SA|