Quicksilver MXII N9045Z accident near Killeen, Texas

Probable cause

A total loss of engine power due to cold seizure for a reason that could not be determined, and the pilot’s subsequent exceedance of the airplane’s critical angle of attack, which resulted in an aerodynamic stall and impact with the ground.

NTSB analysis

The airplane had just departed, and witnesses reported seeing the airplane maneuver without engine power. A dash-cam video of the accident showed the airplane attempt to return to the airport. The airplane flew at a low altitude with its wings rocking side to side. During the final portion of the flight, the airplane’s right wing dropped, and the airplane descended into the ground, consistent with an exceedance of the critical angle of attack leading to an aerodynamic stall. The airplane came to rest inverted next to the westbound highway guard rail. The left wing and fuselage sustained substantial damage.

Examination of the airplane after the accident revealed no preimpact anomalies with respect to the airframe. Examination of the 2-stroke engine revealed scoring between the magneto side piston and its corresponding cylinder, consistent with cold seizure. The cold seizure was likely the result of improper engine warm-up or excessive temperature differential between the coolant entering the engine compared to the coolant exiting the engine. The airplane had been equipped with a larger radiator than the engine manufacturer supplied. The reason for the cold seizure could not be definitively determined.

The pilot was at risk of impairment from combined effects of hydrocodone and chlorpheniramine. However, whether impairing effects of those medications contributed to the accident cannot be determined.

Based on the available evidence, the airplane’s engine lost power due to cold seizure for a reason that could not be determined. While attempting to return to the airport, the pilot exceeded the airplane’s critical angle of attack leading to an aerodynamic stall and impact with the ground.

Text from the NTSB. Open the NTSB docket for CEN20LA417 for the full record.