Accident Description
The aircraft was maneuvering at low altitude to inspect a crop when it crashed in a cotton field. The pilot reported being at an altitude of 4 to 5 feet, with forward flight below transitional lift speed. The rotor RPM began to decrease, accompanied by a drop in engine RPM. In response, the pilot increased rotor pitch, but the rotor RPM continued to decay. The aircraft subsequently struck the ground, rocked forward and backward, and the rotor cut off the tail boom. The pilot then shut down the engine using the mixture lever.
Pilot Statement
The pilot stated that the aircraft was at an altitude of 4 or 5 feet and that forward flight was below transitional lift speed. He noted that the rotor RPM began to reduce and there was also a drop in engine RPM. After increasing rotor pitch, the rotor RPM continued to decay. The aircraft struck the ground, rocked forward and backward, and the rotor cut off the tail boom. The pilot shut down the engine with the mixture lever.
Findings
The aircraft was maneuvering at low altitude when a reduction in rotor and engine RPM occurred. The pilot's attempt to increase rotor pitch did not arrest the rotor RPM decay. The aircraft impacted terrain, resulting in a forward and backward rocking motion and separation of the tail boom by the rotor. The engine was shut down by the pilot after the accident sequence.