Investigation: corroded propeller blade caused KC-130 crash
This incident happened on April 11, 2015. 6 Marine Raiders (out of a force of 3000) and their medic, along with the aircrew were killed. The link describes the cause of the accident and includes a video animation of the incident.
This failure never needed to occur.The Marine Corps investigation found that Blade 4 on Propeller 2 (P2B4, in the report) became unattached, struck the port side of the fuselage, cut straight through the interior of the passenger area of the plane and became lodged in the interior of the starboard side of the plane. This damage kicked off a series of events that led to Propeller 3 colliding with the starboard side of the fuselage and ultimately the plane breaking into three pieces mid-air.
The $#@!pit and the rear of the fuselage crashed into two separate debris fields in a soybean field near Itta Bena, Miss. The middle section of the plane, where the passengers were located, further broke up in the air.
Marine Corps leadership made clear there was nothing the crew or passengers could have done to prevent the mishap or save themselves once the propeller blade broke loose.
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Though no one on the plane could have stopped the events that unfolded, the maintenance community could have prevented them. The investigation found a failure to inspect the propeller during its last depot maintenance period, as well as missed opportunities during squadron-level maintenance to potentially notice the corroded blade.