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Two-piece LP turbine bearing susceptible to abnormal loads

Issue number: AO-2010-066-SI-02
Who it affects: Operators of aircraft fitted with Rolls-Royce RB211-524 engines
Issue owner: Rolls Royce
Operation affected: Aviation: Air transport
Background: Investigation Report AO-2010-066
Date: 16 April 2012

Safety issue description

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.

Proactive Action

Action organisation: Rolls Royce
Action number: AO-2010-066-NSA-032
Date: 13 February 2012
Action status: Closed

As a result of this occurrence and to minimise the risk of potentially hazardous complications associated with blade release events, the engine manufacturer released a non-modification service bulletins NMSB72-AG729 for RB211-524G/H & -T engines, and NMSB72-AG800 for RB211-524 ‘Classic’ engines.

The service bulletins instructed fitment of a more robust LP turbine bearing, part number FB500000, during the next maintenance visit where the turbine module is removed. At the time of writing, the FB500000 bearing had already been installed in over 60% of the RB211-524G/H & -T worldwide engine fleet.

ATSB response:

Adequately addresses the safety issue.

   
Current issue status: Adequately addressed
Status justification:

More robust bearing significantly reduces likelihood of uncontained consequences associated with LP turbine blade failure.

 
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Last update 24 February 2014