On July 10, 2001, a Bell 47 (registration N8478D) was involved in an aviation accident near Indianola, MS. Investigators recorded the probable cause as: The pilot's improper use of flight controls during an autorotation that resulted inn the collapse of the skids and cross tube assembly. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot reported engine power loss at 500 feet while en route to a spraying field. After failed restart attempts, he autorotated to a field, but the helicopter rolled over on its right side during touchdown. Examination revealed metal particles and a connecting rod cap wedged in the engine.
Accident Sequence
The pilot was en route to the next field to be sprayed when, at an altitude of 500 feet, the engine lost power. Attempts to restore full power were unsuccessful, prompting the pilot to select a nearby field for an emergency landing. During the autorotative touchdown, the helicopter rolled over onto its right side.
Examination Findings
Subsequent examination of the engine revealed metal particles in the oil pump screen and oil filter element. Further inspection showed that the #1 cylinder connecting rod cap was wedged between the second crankshaft lobe and the engine case. The engine had accumulated 935.1 hours since its last major overhaul.
Examination of the helicopter structure disclosed that the landing skid and cross-tubes were fractured into several pieces. Fracture analysis indicated that all fractures were due to overload.