Aviation safety investigations & reports

Uncontained engine failure and air turn-back near San Francisco Airport, USA, 30 August 2010

Investigation number:
AO-2010-066
Status: Completed
Investigation completed

Summary

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On 30 August 2010 at approximately 2330 Pacific Daylight Time, a Qantas Boeing 747-438 aircraft, registered VH-OJP, departed San Francisco International Airport on a scheduled passenger service to Sydney, Australia. As the aircraft passed through 25,000 ft, the aircraft's number-4 engine failed, resulting in the puncturing of the engine casing and nacelle and the release of debris. The engine was shut down and the flight crew returned the aircraft to San Francisco International Airport. There were no injuries.

An investigation conducted by the engine manufacturer found that the engine failure was initiated by the fatigue fracture of a single stage-2 low pressure (LP) turbine blade. The ensuing rotor imbalance caused the LP turbine bearing to fail, which ultimately resulted in the uncontained release of debris.

As a result of this occurrence, the engine manufacturer released non-modification service bulletins NMSB72-AG729 and NMSB72-AG800; instructing operators of RB211-524 engine variants to fit a more robust LP turbine bearing, so as to reduce the likelihood of catastrophic engine failure resulting from rotor imbalance.

Download Final Report
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Alternate: [Download  DOC: 5.03MB]
 

Preliminary

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Preliminary report released 25 October 2010

On 30 August 2010 at approximately 2330 Pacific Daylight Time, a Boeing 747-438 aircraft, registered VH-OJP, departed San Francisco International Airport on a scheduled passenger service to Sydney, Australia. As the aircraft passed through 25,000 ft, the aircraft's number-4 engine sustained an internal mechanical failure, resulting in the energetic release of debris and puncturing of the engine casing and nacelle. The engine was shut down and the flight crew returned the aircraft to San Francisco, where it landed without further incident.

 

 

Updated: 29 August 2011

Disassembly and examination of the number-4, Rolls-Royce RB211-524 engine at Hong Kong Aero Engine Services Limited (HAESL) has been completed under supervision of ATSB investigators, as well as representatives from the engine manufacturer, airframe manufacturer, and aircraft operator. Based on the outcomes of the disassembly, numerous engine components were retained for further, detailed testing and analysis by the engine manufacturer.

The manufacturer's investigation has concluded that the fracture and release of a low-pressure turbine (LPT) blade was likely to have initiated the engine failure.  This produced rotor imbalance forces that resulted in significant damage to the LPT support bearing.  The bearing damage promoted additional secondary damage to core turbine hardware, to the extent that a turbine casing was ruptured and low energy blade and nozzle guide vane debris was released.

An alternative bearing standard, which featured a more robust construction, had previously been introduced as an optional replacement part for reasons of continuity of supply for production. This bearing standard was not fitted in the event engine.  To minimise the risk of complications arising from rotor imbalance, the engine manufacturer is working with operators to embody this more robust bearing standard into engines, which, at the time of writing, is installed in more than 50% of the worldwide fleet.  The engine manufacturer has issued an Alert Non-Modification Service Bulletin (NMSB72-AG729) to instruct the installation of this improved bearing across the remainder of the fleet.   

 

 

Updated: 7 September 2010

The ATSB investigation team has completed its preliminary examination of the engine in San Francisco. The engine is now being shipped to an engine facility in Hong Kong for a detailed disassembly and examination, under the supervision of ATSB investigators. The investigation is ongoing and also includes:

  • detailed analysis of recorded flight data, with particular focus on analysis of engine operational parameters
  • examination of aircraft maintenance documentation
  • interviews with crew and passengers.

This page will provide future updates on any significant developments as they come to hand.

Download Preliminary Report
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General details
Date: 30 August 2010   Investigation status: Completed  
Time: 0600 UTC    
Location   (show map): near San Francisco International Airport USA   Investigation type: Occurrence Investigation  
State: International   Occurrence type: Engine failure or malfunction  
Release date: 16 April 2012   Occurrence class: Technical  
Report status: Final   Occurrence category: Serious Incident  
  Highest injury level: None  

Aircraft details

Aircraft details
Aircraft manufacturer The Boeing Company  
Aircraft model 747  
Aircraft registration VH-OJP  
Serial number 25545  
Type of operation Air Transport High Capacity  
Damage to aircraft Minor  
Departure point San Francisco, USA  
Destination Sydney, NSW  
Last update 14 November 2018