Aviation safety investigations & reports

de Havilland Canada DHC-8-202, VH-SDA, 407 km NW Cairns, Aero. 25 June 2009

Investigation number:
199903738
Status: Completed
Investigation completed

Summary

While cruising at flight level 220 between Kimmi and Ablok, approximately 220 NM north-west of Cairns, the crew of the Dash 8 heard a muffled sound that was followed by an increase of the left engine inter turbine temperature. The crew reduced the engine power and returned the aircraft to Cairns.

The engine examination revealed that the reported problem was the result of a failure of the number 5 bearing. The bearing cage contained two cracks and was open. Some roller pockets in the bearing cage were enlarged and distorted, which allowed the rollers to rotate in the plane of the cage. Some other rollers were immobilised and contained large flats. Six of the 12 rollers had a smaller diameter than the rest. Their surface was abraded and smeared, consistent with heavy contact loads.

Because of several similar failures, the engine manufacturer had issued service bulletin number 21472R2, on 25 February 1999, introducing an improved number 5 bearing. The service bulletin advised that engines of serial numbers subsequent to the failed engine were already fitted with the new bearing. It further recommended that number 5 bearings on all other Pratt & Whitney PW100 engine models should be replaced when the engines were disassembled and access was available. The improved bearing had not been installed on this engine.

General details
Date: 25 June 1999   Investigation status: Completed  
Time: 1230 hours EST    
Location   (show map): 407 km NW Cairns, Aero.    
State: Queensland   Occurrence type: Abnormal engine indications  
Release date: 15 November 2000   Occurrence category: Incident  
Report status: Final   Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer de Havilland Canada  
Aircraft model DHC-8  
Aircraft registration VH-SDA  
Serial number 482  
Type of operation Air Transport Low Capacity  
Damage to aircraft Minor  
Departure point Cairns, QLD  
Departure time 1130 hours EST  
Destination Horn Island, QLD  
Last update 13 May 2014