DURING ROTATION THE #2 ENG SUSTAINED AN EXPLOSIVE RUPTURE OF ITS COMPRESSOR REAR FRAME(CRF). THE CREW OBSERVED A RAPID DROP IN THE #2 ENG PERFORMANCE PARAMETERS & THE ILLUMINATION OF THE #2 ENG THRUST REVERSERS 'UNLOCK AND IN TRANSIT' LITES. THE CREW DISCHARGED A FIRE BOTTLE. AFTER THE ENG WAS SHUT DOWN & THE FUEL DUMPED, THE CREW LANDED THE ACFT WITHOUT FURTHER INCIDENT. THE ENG DAMAGE WAS PRIMARILY CONFINED TO AN AXIALLY RUPTURED OUTER CASING OF THE CRF. THE CRF HAD FRACTURED AS A RESULT OF A HIGH-STRESS(LOW-CYCLE) FATIGUE. THE FATIGUE ORIGINATED AT A ZONE OF MICROPOROSITY IN THE IGNITOR PAD AREA OF THE CRF OUTER CASING. TOTAL NUMBER OF CREW & PASSENGERS NOT REPORTED.

The National Transportation Safety Board determines the probable cause(s) of this incident as follows:

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