NTSB Identification: ENG08IA002
Scheduled 14 CFR Part 121: Air Carrier operation of Southwest Airlines
Incident occurred Saturday, November 17, 2007 in Greenville, TX
Probable Cause Approval Date: 06/22/2009
Aircraft: BOEING 737-300, registration: N676SW
Injuries: 138 Uninjured.

NTSB investigators traveled in support of this investigation and used data obtained from various sources to prepare this aircraft incident report.

The airplane experienced a failure of the No. 2 engine while climbing through flight level (FL) 250 to FL 330. The flight crew reported feeling severe vibration, pulled both throttles back to idle, declared an emergency, made an air turn back and performed an uneventful single-engine landing. Examination of the engine revealed that all the fan blades exhibited heavy airfoil damage, with several fractured near the platform. The forward and rear spinner cones were no longer attached to the fan disk and a large penetration hole was noted on the right-hand side of the fan cowl, just forward of the engine fan case. Examination of the airplane revealed impact marks along the right side of the fuselage and the right-hand horizontal stabilizer. None of the fuselage impacts were through to the cabin. The pieces of the forward and rear spinners cones that exited the engine were never recovered. Metallurgical examination of the fracture surfaces of the fan blades and the fragments of the rear spinner aft flange revealed no preexisting fatigue-type mechanism and all the fractures were consistent with overstress. Four sequential fan blade spacers were distorted consistent with a severe axial load rearward applied to the spacers by the rear spinner cone prior to the spinner cone release; however, no determination could be made as to the initial failure or what may have impacted the spinner cone.

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

A total loss of engine power due to the No. 2 engine experiencing a release of its fan spinner through the fan cowl as a result of an unidentified object striking the spinner, separating it from the fan disk and causing the spinner to be ingested into the fan blades.

Full narrative available

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