What happened
A flight test was being conducted to evaluate the handling properties of an aircraft equipped with an experimental four-bladed propeller configuration. The specific objective of the mission was to observe the aircraft's behavior following a sudden reduction of power from throttle to idle at an altitude of 50 feet above ground level. While the maneuver had been performed successfully twice earlier in the flight, the third attempt resulted in an accident.
During this final approach, the pilot reduced the throttles more rapidly than during previous passes. This action caused the aircraft to yaw and the wing to drop. The right landing gear made contact with the runway first, followed by the left and nose gears. The impact was severe enough that all three landing gear components sheared off from the airframe. Following the initial contact, the aircraft slid across the ground for 975 feet before coming to a halt off the runway.
Findings
Investigations into the mechanical state of the propellers following the accident showed no evidence of prior abnormalities or misadjustments. The investigation concluded that the primary factors involved were an improper descent rate and a delay in remedial actions by the pilot. Ultimately, the hard landing resulted in structural forces that exceeded the design stress limits of the aircraft's landing gear.