Incident Overview
A flight instructor and pilot were conducting traffic patterns in a helicopter. After completing two patterns, during the third takeoff for another approach, the instructor felt a thump in the airframe. He immediately initiated an autorotation and landed in a wooded area.
Post-Accident Examination
Examination of the helicopter revealed that the tail rotor gearbox and tail rotor assemblies were missing. According to the operator, both assemblies were recovered the following day, but the National Transportation Safety Board (NTSB) was not notified of the recovery. The damaged components were subsequently examined by the operator and then destroyed.
Mechanic's Observations
A mechanic reported that one rotor blade had failed in the vicinity where Airworthiness Directive (AD) 59-05-10 applied. This AD required a daily inspection of the tail rotor blades for cracks.
Pilot's Statement
The pilot stated that an inspection of the blades had been completed prior to the flight.