What happened
On February 20, 1956, a scheduled Capital Airlines flight departing from Willow Run Airport in Detroit, Michigan, was en route to Chicago. The aircraft, a commercial airliner, departed at 0700 under a visual flight rules plan following a standard weather briefing. During the flight, the crew maintained a routine progress toward their destination.
As the aircraft approached Chicago, the crew notified the tower that they had crossed the shoreline and later reported passing Kedzie. The flight was cleared for landing on runway 3ically 31R. While performing a right turn to align with the final approach, the plane appeared to be descending normally at an altitude between 25 and 50 feet above the ground near Cicero Avenue. Suddenly, the aircraft began to decelerate and experienced a rapid descent. The aircraft struck the ground in a slightly nose-up position several hundred feet before reaching the runway threshold. Upon impact, the upper portion of the fuselage broke open near the wing spar attachment. As the plane moved down the runway, the landing gear retracted, causing the aircraft to slide on its belly for 1,626 feet past the initial impact point. There were no fatalities among the occupants, and although emergency responders arrived while evacuation was still underway, no fire broke out.
Findings
Investigations into the accident identified a mechanical failure involving the propeller control switches as the primary factor. It was determined that at least two of the landing gear actuated switches, which influence propeller operation, malfunctioned. This allowed the 21-degree pitch stops to become ineffective.
During the final approach, the propellers transitioned into a ground fine pitch range. When the crew noticed warning lights indicating a change in pitch, the first officer responded by quickly advancing all four throttles. This rapid movement caused the propeller governor control to shift the blades to a four-degree pitch position, which created significant propeller drag and a sudden loss of wing lift.