On May 15, 1997, a Bell 47G-3B (registration N8491E) was involved in an aviation accident near Snohomish, WA. Investigators recorded the probable cause as: the pilot's encounter with of a loss of tail rotor effectiveness (LTE) situation, and his subsequent inadequate remedial action. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter pilot in training experienced an uncommanded right yaw while aborting a practice landing. Despite corrective inputs, the helicopter rotated violently and impacted terrain. FAA inspection found no mechanical malfunction.
Incident Overview
A commercial helicopter pilot upgrade training flight ended in an accident when the pilot lost control during an abortive landing. The pilot, who held an instructor's endorsement granting helicopter solo privileges but was not yet rated for helicopters, was practicing landings in wind conditions conducive to an unanticipated right yaw—a phenomenon known as loss of tail rotor effectiveness (LTE).
Sequence of Events
As the pilot executed a turn to downwind while aborting a practice landing, the helicopter made an uncommanded right turn. Despite the pilot's application of left pedal and forward cyclic, the helicopter continued to rotate violently until it struck the ground on its left side.
Post-Accident Examination
Federal Aviation Administration (FAA) inspectors examined the helicopter at the accident site. They reported no evidence of a mechanical malfunction and noted that the tail rotor system was intact.