Amateur-built RV7 N307AB accident near Hurricane, Utah

Probable cause

The pilot’s aerobatic maneuver leading to airspeeds above the airplane’s never exceed speed, which resulted in rudder flutter and an in-flight breakup.

NTSB analysis

**This report was modified on March 20, 2024. Please see the docket for the original report.**

The airline transport pilot was conducting a local personal flight in the experimental amateur built airplane, with one passenger on board. Several witnesses located near the accident site reported that they heard the airplane's engine and that it sounded like it was making power changes. The witnesses added that they then saw airplane debris floating in the air. One witness stated that the engine was running during the entire descent and that he saw the airplane spiraling and descending in a cork-screw type maneuver. Another witness reported seeing the airplane inverted at a low altitude just before impact.

Postaccident examination of the airplane revealed that the vertical stabilizer, with about half the upper rudder still attached, separated from the airplane and was recovered mostly intact farthest from the main wreckage. The vertical stabilizer separated in a leading-edge-left direction in overload. The damage to the horizontal stabilizers and elevators was consistent with a downward failure in positive overload. The damage observed on the wings was consistent with a downward failure in negative overload. Additionally, there were no indications of any preexisting cracks in or anomalies with the vertical stabilizer, horizontal stabilizers, elevators, or wing structures, and no preaccident anomalies were observed that would have precluded normal control of the airplane.

The recovered photographic information showed the pilot performed a split-S maneuver that likely caused the airplane’s speed to increase rapidly. The speed increased above VNE and excited the rudder flutter mode, causing the vertical stabilizer to separate due to overload. The photographs confirmed the vertical stabilizer separation as the airplane neared completion of the maneuver. The rudder flutter mode excited the horizontal stabilizer flutter mode causing them to fail downward due to overload. The airplane then rapidly pitched over, buckling the right wing and separating the left wing. The photographic evidence confirmed the rapid pitch over after the separation of the vertical stabilizer.

Although doxylamine was detected in the pilot's liver it was not detected in the blood; therefore, it is unlikely that it caused any performance decrements that would have affected the pilot at the time of the accident.

Text from the NTSB. Open the NTSB docket for WPR16FA036 for the full record.