Incident Description
The airplane was climbing through flight level (FL) 250 to FL 330 when the No. 2 engine failed. The flight crew reported severe vibration, pulled both throttles back to idle, declared an emergency, executed an air turn back, and performed an uneventful single-engine landing.
Examination Findings
Examination of the engine revealed heavy airfoil damage to all fan blades, with several fractured near the platform. The forward and rear spinner cones were no longer attached to the fan disk. A large penetration hole was noted on the right-hand side of the fan cowl, just forward of the engine fan case. Inspection of the airplane showed impact marks along the right side of the fuselage and the right-hand horizontal stabilizer, but none of the fuselage impacts penetrated through to the cabin. The pieces of the forward and rear spinner cones that exited the engine were never recovered.
Metallurgical Analysis
Metallurgical examination of the fracture surfaces of the fan blades and fragments of the rear spinner aft flange revealed no preexisting fatigue-type mechanism; all 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.