Narrative:A Northwest Airlines Martin 2-0-2 departed from Minneapolis at 09:46 on a local flight. The purpose of the flight was a six-month instrument competency check of the captain. The weather was clear and visibility was unlimited. Following takeoff two simulated ILS approaches were made to the airport and at 10:25 the crew radioed the control tower that this phase of the check flight was completed. After departing the Minneapolis area, the aircraft was first seen near Center City, 43 miles northwest of Minneapolis. At this time it was making a steep left turn at an altitude estimated to he between 4,000 and 5,000 feet, and landing gear was down. At the completion of this turn a shallow climb was started. The crew then rolled to a partially inverted position and started a steep dive. After losing approximately 2,500 feet in the dive, an apparently normal recovery was made to a level flight attitude and the aircraft proceeded in a northeasterly direction. Shortly thereafter it was seen to make two or three pitching oscillations about its lateral axis. During each oscillation approximately 400 feet in altitude was lost and a noise was heard such as is usually associated with a surge of engine power. The aircraft continued on a northeast heading. Two miles south of Almelund, the aircraft was seen to make a shallow right turn of approximately 270 degrees and once more to return to a level attitude heading in a northwesterly direction. The aircraft had been gradually losing altitude, and the right propeller was observed to be turning slowly during the latter part of the flight. Nearing Almelund and at an altitude of approximately 500 or 600 feet above the ground, a steep right turn was begun. Altitude was lost rapidly and after turning approximately 90 degrees, the aircraft's right wing struck the ground and the plane crashed.
PROBABLE CAUSE: "The unwanted reversal of the right propeller during flight, as a result of which the crew was unable to maintain control of the aircraft."
Loss of control
» CAB File No. 1-0119