Accident Sequence
A flight instructor and a pilot conducted a normal takeoff from Runway 34 to perform right closed traffic. During the flight, a UH-60 helicopter was executing an approach from the southwest to the threshold of Runway 34. To make way for the helicopter, the pilot extended the intended touchdown point by approximately 1,000 feet.
The helicopter transitioned to hovering flight near the runway threshold about 30 seconds before the accident airplane. After a short delay, the UH-60 air-taxied to the ramp. When the accident airplane was approximately 20 feet above the ground, it suddenly rolled to the right at a rate faster than a full application of aileron could counteract, and the right wing contacted the ground.
Helicopter Proximity and Wake Turbulence
Witness statements indicated that the UH-60 was located between 100 and 600 feet from the accident airplane at the time of the event. According to the Aeronautical Information Manual, every aircraft generates vortices that can cause an uncommanded roll exceeding the roll-control authority of an encountering airplane. Landing helicopters produce a pair of strong, high-speed trailing vortices similar to those of larger fixed-wing aircraft. The manual advises that pilots of small aircraft use caution when operating behind landing helicopters.