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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.

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[ Download PDF: 971KB]
General details
Date: 25 July 2007 Investigation status: Completed 
Time: 1035 CST  
Location   (show map):23 km NNE Ardrossan Investigation type: Occurrence Investigation 
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 details
Aircraft manufacturer: Cessna Aircraft Company 
Aircraft model: 441 
Aircraft registration: VH-OAA 
Serial number: 4410102 
Type of operation: Air Transport Low Capacity 
Damage to aircraft: Nil 
Departure point:Port Augusta, SA
Destination:Adelaide, SA
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Last update 14 November 2018