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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.

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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.

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Safety issues

AO-2010-066-SI-01 - AO-2010-066-SI-02 -  

Turbine blade fatigue endurance limit

High service time stage-2 LP turbine blades were susceptible to a reduction in fatigue endurance as a result of vibratory stresses sustained during operation at speeds close to the maximum.

Issue Number:AO-2010-066-SI-01
Who it affects:Operators of aircraft fitted with Rolls-Royce RB211-524 engines
Status:Adequately addressed


 

Two-piece LP turbine bearing susceptible to abnormal loads

LP turbine support bearings (part numbers LK30313 and UL29651) showed increased susceptibility to breakdown and collapse under vibratory stress conditions associated with LP turbine blade release.

Issue Number:AO-2010-066-SI-02
Who it affects:Operators of aircraft fitted with Rolls-Royce RB211-524 engines
Status:Adequately addressed

 

General details

Date: 30 Aug 2010 Investigation status: Completed 
Time: 0600 UTC Investigation type: Occurrence Investigation 
Location:near San Francisco International Airport USA Occurrence type:Engine failure or malfunction 
State: International Occurrence class: Technical 
Release date: 16 Apr 2012 Occurrence category: Serious Incident 
Report status: Final Highest injury level: None 
Expected completion: Dec 2011  
 

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
 
 
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Last update 25 March 2014