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Safety Action

Summary

The engine manufacturer issued Service Bulletin SB72-E181 on 6 August 2003 to provide a long-term solution to the uneven blade root friction problem. That SB introduced a revised dry film lubricant (DFL) to be used as an alternate blade root lubrication coating. Incorporation of the SB is indicated by a change in blade part number.

The manufacturer has also revised the manufacturing process for the HPC blades, changing the blade root machining process from broaching to milling.

A new design HPC blade drum has been developed to prevent blade loading slot cracking. Service Bulletin SB72-E106 was issued on 7 March 2003 to include the application of the improved DFL to the first stage HPC blade root dovetails of those blade drums at manufacture.

As an interim measure, the manufacturer has revised the inspection limits for blade root damage and scores, and has instigated blade root DFL removal and replacement at each module overhaul. An ultrasonic, non-destructive-inspection procedure, that can detect blade root cracking without removing the engine from the aircraft, has also been developed.

The manufacturer reported that an update to these solutions would be supplied to all operators.

 
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