NTSB Identification: ENG09IA002
Scheduled 14 CFR Part 121: Air Carrier operation of Delta Air Lines
Incident occurred Friday, January 02, 2009 in Atlanta, GA
Probable Cause Approval Date: 10/09/2012
Aircraft: BOEING 777, registration: N864DA
Injuries: 257 Uninjured.
NTSB investigators traveled in support of this investigation and used data obtained from various sources to prepare this aircraft incident report.
The Boeing 777 airplane experienced a contained fan blade fracture in the No. 2, right, engine, a Rolls-Royce plc RB.211 Trent 895-17 turbofan, during the takeoff roll at the Hartsfield Jackson Atlanta International Aiport. The examination of the fan blade revealed it had fractured from a fatigue crack that had initiated at the intersection of the convex side aft corner of the shear key slot and bedding flank. The examination of the fan blade also revealed the plasma spray coating was deteriorated and the dry film lubricant was almost completely gone. A survey by the engine manufacturer of the operator's 777 engine usage indicated that because of the loads and lengths of the flights, the operator was operating their Trent 895-17 engines at higher thrust levels with correspondingly high fan rotational speeds, which were still within the engine's operating limits, than any other operator. The survey also indicated the operator was operating its 777 and Trent engines significantly more hours per cycle than any other Trent 895 operator. An analysis by the engine manufacturer indicated that the blade fracture was caused by a combination of the breakdown of the lubrication system and residual fatigue life usage in the blade root following the last overhaul coupled with the high operating stresses in the fan blade from the high thrust settings.
The National Transportation Safety Board determines the probable cause(s) of this incident to be: The fan blade fractured due to a fatigue crack that was the result of the combination of the breakdown of the fan blade lubrication system and residual fatigue life usage following the last overhaul of the fan blade. Contributing to the fracture was the inadequate lubrication schedule established by the engine manufacturer that was not reflective of the operator’s use of the engine. Full narrative available
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