On April 19, 1999, about 0730 central daylight time, a Bell 47-G3B, N32PH, registered to Provine Helicopter Service, Inc., operating as a 14 CFR Part 137 aerial application flight, crashed while attempting a liftoff from a truck mounted platform near Thomastown, Mississippi. Visual meteorological conditions prevailed and no flight plan was filed. The helicopter sustained substantial damage and the commercially-rated pilot and a passenger reported no injuries. The flight originated about 30 minutes before the accident. The pilot stated he departed with the land owner for an orientation flight over the tract to be sprayed. Upon completion of the orientation flight, he returned to the "nurse truck" and made an approach to deplane the land owner. He was not content with his landing skid placement on the platform and pulled up for a second approach, when the helicopter started an uncommanded yaw, followed by an uncontrolled rotation. He stated he thought the passenger had stepped on the right anti-torque pedal. He maneuvered the helicopter away from the truck, but the main rotor blades collided with a small tree, the right landing skid hit the terrain hard enough to collapse, and the aircraft came to rest on its right side. According to the two-man ground crew, as the helicopter was lifting off the platform for better positioning on the platform, they heard a "loud bang similar to a shotgun blast". They saw a piece of the aircraft fly away and the tail rotor stopped turning. The helicopter performed multiple rotations, tilted toward its right side, and impacted a stand of small trees with its main rotor blades. The helicopter came to rest on its right side within the trees. Subsequent examination of the accident site and interview of the pilot, ground crew, and land owner by Federal Aviation Administration (FAA) inspectors, revealed that the pilot was making a downwind approach to the platform in order to position the passenger near the ladder to expedite his exit off the platform. The wreckage revealed the throttle was fully open and the right anti-torque pedal was full forward. A 16-inch section of tail rotor drive shaft located in the plane of the main rotor tips was missing and the tail boom truss had sustained a main rotor blade strike. One of the main rotor blade tips (outer 4-6 inches) had witness marks that would be consistent with striking the tail rotor shaft. Except for the aforementioned, the inspectors could find no mechanical malfunctions of the pilot's flight or engine controls, the engine or its components, or the transmission or drive train to the main or tail rotor systems. The FAA operations inspector stated, "It appears that the pilot through cyclic and collective control input caused the rotor blades to make contact with the tailboom and tailrotor drive shaft".