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The PA31-350 aircraft was in cruise flight, at 8,000 ft, when the flight crew noticed that the propellers went out of synchronisation. Adjustments were made to correct the problem but were unsuccessful. Following right engine RPM fluctuations, the crew shut the engine down, feathered the propeller and conducted a single engine landing.

During the subsequent disassembly of the engine, the crankshaft was noted to have fractured at the number-6 connecting rod journal.

The engine components were sent to the ATSB for further technical analysis. Analysis of the fracture indicated that fatigue cracking had initiated below the surface of the journal, associated with a discontinuity in the nitrided surface zone, at the transition from the journal to the forward fillet radius. The number-6 connecting rod bearing inserts had been destroyed during operation; the remnants included flattened fragments of steel backing material. In addition, fatigue crack growth had commenced at the centre of the connecting rod cap, most probably after the bearing inserts had failed.

Because of the small amount of bearing debris available for testing, the reason the number-6 bearing inserts failed could not be determined.

This engine failure is one of a number of events being used in a detailed safety study of failures to high powered piston engines. On completion, the results will be available on the ATSB website www.atsb.gov.au or from the Bureau on request.

General details
Date: 14 December 2001 Investigation status: Completed 
Time: 1650 hours ESuT  
Location   (show map):83 km NE Warrnambool, Aero. Investigation type: Occurrence Investigation 
State: Victoria  
Release date: 18 July 2002  
Report status: Final Occurrence category: Incident 
 Highest injury level: None 
Aircraft details
Aircraft manufacturer: Piper Aircraft Corp 
Aircraft model: PA-31 
Aircraft registration: VH-JCH 
Serial number: 31-8152106 
Type of operation: Air Transport Low Capacity 
Damage to aircraft: Nil 
Departure point:Avalon, VIC
Departure time:1624 hours ESuT
Destination:Portland, VIC
Crew details
RoleClass of licenceHours on typeHours total
Co-Pilot/1st OfficerCommercial173.6444
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Last update 13 May 2014