Incident Details
The aircraft departed MCAS Cherry Point-Cunningham Field in the early afternoon on a personnel transfer mission to El Centro NAS, California. While cruising at an altitude of 20,000 feet, the number four blade on the number two propeller detached. The liberated blade struck the left side of the fuselage, penetrated the cabin, exited the right side, and impacted the right stabilizer, causing it to separate. The resulting catastrophic structural failure led the cockpit to detach. The aircraft entered an uncontrolled descent and crashed in a soybean field located 11 kilometers southwest of Itta Bena, Mississippi. Impact forces and a post-crash fire destroyed the aircraft, killing all 16 occupants.
Occupants
The crew consisted of pilot Maj Caine M. Goyette, copilot Cpt Sean E. Elliott, flight engineers S/Sgt Joshua Snowden and Sgt Owen J. Lennon, gunnery sergeants G/Sgt Mark A. Hopkins and G/Sgt Brendan C. Johnson, crewmasters Sgt Julian M. Kevianne and L/Cpl Daniel I. Baldassare. Passengers included Cpl Collin J. Schaaff, S/Sgt William J. Kundrat, S/Sgt Robert H. Cox, S/Sgt Talon R. Leach, Sgt Chad E. Jenson, Sgt Joseph J. Murray, Sgt Dietrich A. Schmiernan, and PO Ryan Lohrey.
Investigation Findings
The investigation determined the cause of the mishap to be an in-flight departure of the number four blade from the number two propeller (designated P2B4). Post-mishap analysis revealed that a circumferential fatigue crack caused the blade fracture and liberation. The fatigue crack propagated from a radial crack originating from intergranular cracking (IGC) and corrosion pitting. Anodize coating was found within the corrosion pitting and IGC band near the crack origin, indicating the band was present and not removed during the last overhaul at Warner Robins Air Logistics Complex (WR-ALC) in fall 2011. The investigation concluded that the failure to remediate the corrosion pitting and IGC was due to deficiencies in the propeller blade overhaul process at WR-ALC, which existed in 2011 and continued until the process shutdown in fall 2017. The investigation also examined whether operational or intermediate-level inspections could have detected the underlying conditions before the mishap. It concluded that while such inspections exist, it cannot be quantifiably determined that they would have detected the causal condition, because the growth rate of an IGC radial crack is unpredictable. No evidence exists to determine when the radial crack grew to a detectable area beyond the bushing, though there is a possibility it could have been detected if the crack had grown past the bushing and an off-wing eddy current inspection was performed.