Jump to Content

Safety Action

Summary

Local safety action

In response to other JT9D blade failures from trailing edge cracks, the engine manufacturer implemented improvements to the eddy-current techniques used to inspect the blades after overhaul. The improvements included the addition of a new eddy-current inspection requirement after fan blade patch repairs, changes to the probe scanning methods and the use of a chart-recorder device to produce a 'hard-copy' of the test results for post-inspection review. The blade fracture on engine P-716610 occurred on a component that was repaired and inspected before the technique improvements and relevant engine manual changes were made.

The engine manufacturer is revising the relevant engine manuals to include the use of an enhanced 3-pass eddy current inspection procedure in lieu of the single pass procedure. This procedure provides a greater degree of confidence for the detection of small defects. The issue of these engine manual revisions is planned for early 2003.

An all-operator communication (AOW) was issued by the engine manufacturer on 19 July 2002, providing for a temporary revision of the engine manuals to incorporate the 3-pass eddy current inspection procedure, prior to the full revision of the engine manuals as mentioned above. The AOW also recommended the re-inspection of all fan blade leading and trailing edges at next overhaul, using the 3-pass eddy current procedure.

After the engine failure, the aircraft operator implemented a once-off fleet-wide inspection of the fan blade trailing edges using an eddy-current technique. No other similar defects were found. The operator has also implemented an engineering instruction requiring that all new or lease engines introduced into the fleet will automatically be flagged as requiring a blade trailing edge eddy-current inspection.

 
Share this page Comment