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On 27 November 2006, a Beechcraft King Air 200 aircraft, registered VH-XDB and carrying two crew and six passengers, was on a flight from Mount Hale to Perth, Western Australia. Shortly after commencing the decent into Perth airport, the right engine failed catastrophically.

An engineering examination of the failed Pratt and Whitney Canada PT6A-41 turboprop engine was performed and revealed that the first-stage 'sun' and 'planet' gear set within the propeller reduction gearbox had decoupled from the power turbine. The decoupling allowed the power turbine to overspeed, which resulted in destruction and shedding of the turbine blades. Several blade fragments punctured the outer gas generator case.

A metallurgical examination of the failed first-stage gear set revealed that a mismatch in service histories between the sun gear and planet gears was the most likely contributor to the failure. The engine manufacturer had been alert to the occurrence of reduction gearbox distress due to gear mismatching at overhaul.

Following this incident, the aircraft operator initiated a review of their system of maintenance with respect to monitoring of life-limited engine components, for all PT6A engines in their fleet.

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General details
Date: 27 November 2006 Investigation status: Completed 
Time: 1800 WST  
Location   (show map):93km N of Perth Airport Investigation type: Occurrence Investigation 
State: Western Australia Occurrence type: Engine failure or malfunction 
Release date: 24 June 2009 Occurrence class: Technical 
Report status: Final Occurrence category: Incident 
 Highest injury level: None 
Aircraft details
Aircraft manufacturer: Beech Aircraft Corp 
Aircraft model: 200 
Aircraft registration: VH-XDB 
Serial number: BB-533 
Type of operation: Air Transport Low Capacity 
Damage to aircraft: Minor 
Departure point:Mt Hale. WA
Destination:Perth, WA
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Last update 14 November 2018