Accident Overview
During a firefighting operation, a helicopter was descending into a hover over a pond intended for an aerial fire bucket refill site. As the pilot began to level off in the hover, a loud noise was heard accompanied by an "accelerated vibration." Shortly thereafter, the helicopter initiated an uncommanded right spin. The pilot responded by closing the throttle and executing an autorotational landing, which resulted in the helicopter settling in approximately three to four feet of water.
Post-Accident Inspection
A post-accident examination revealed that the tail rotor driveshaft had failed due to torsional overload. Additionally, one of the tail rotor blades exhibited delamination, which was determined to be a consequence of contact with the water during the hover.
Flight Details
The helicopter was engaged in firefighting operations, utilizing a bucket to collect water from the pond. No information regarding the aircraft type, registration, operator, or specific date of the accident is available from the source. The pilot's actions in response to the emergency were limited to closing the throttle and performing an autorotation, which successfully brought the helicopter to a controlled landing in the water.
Examination Findings
The primary failure identified was the tail rotor driveshaft, which broke under torsional overload. The tail rotor blade delamination was secondary, resulting from water contact. The source does not provide additional details on the sequence of events or contributing factors beyond these physical findings.