Primary finding
Probable cause
A bystander’s inadvertent contact with the propeller while the engine was running.
Investigator assessment
Analysis narrative
The pilot made a fuel stop as part of a solo cross-country flight. The pilot’s mother and sister had come out to the airport to visit. After fueling the airplane, his mother and sister returned to their car. The pilot conducted his preflight, started the engine, and was completing the checklist when he “heard and felt a violent thud.” He looked up to see his mother “sprinting towards the car.” The pilot shutdown the airplane. The pilot’s mother had returned to the airplane unexpectedly and was struck by the propeller resulting in a serious injury to her left arm. The airplane exhibited no obvious damage.