NTSB Issues Urgent Recommendations for GE CF6-45/50 Turbofans
The NTSB issued two urgent safety recommendations to the FAA that pertain to th

The NTSB issued two urgent safety recommendations to the FAA that pertain to the General Electric GE CF6-45/50 series turbofan engine, which is found on the Airbus A300B, DC-10-15/-30, Boeing 747-200 and -300 and KC-10. The first recommendation asks that the FAA require operators of aircraft equipped with this engine to immediately perform blade borescope inspections (BSI) of the high-pressure turbine rotor every 15 flight cycles until the current turbine disk can be redesigned and replaced with one that can withstand the unbalance vibration forces from the high-pressure rotor. Second, the Safety Board wants the FAA to require GE to immediately redesign the disk.

The NTSB issued an additional recommendation for a requirement that operators perform fluorescent penetrant inspections of CF6-45/50 low-pressure turbine (LPT) stage-three disks at every engine shop visit and another recommendation to require installation of the replacement disk once it is available.

All four recommendations apply to the LPT stage -three rotor disk in the GE CF6-45/50 series engines that can fail unexpectedly when excited by high-pressure rotor unbalance. This could then lead to an uncontained engine event. In fact, the NTSB is aware of four uncontained engine failures due to this problem.