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.
More robust bearing significantly reduces likelihood of uncontained consequences associated with LP turbine blade failure.
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.
Adequately addresses the safety issue.
