Introduction
A helicopter experienced rotor blade contact with the ground and tail boom during a training flight. The incident occurred after the aircraft landed following an autorotation approach. The flight was instructional, intended to prepare a rated pilot for a flight instructor rating.
Flight Details
The aircrew consisted of an instructor pilot (IP) and a student pilot. After practicing several autorotation approaches, the helicopter was landed. The IP stated that after touchdown, he and the student were engaged in a discussion when they heard a loud "pop." The IP deplaned and inspected the helicopter but found no irregularities. The crew then took off and performed another autorotation. After touchdown, the collective was lowered, and the helicopter pitched left and forward. The rotor blades contacted the ground and the tail boom.
Investigation Findings
An investigation revealed that the left front shock strut damper assembly, part number 269A3150-5, had failed. The total time on the part was 3,614 hours. A metallurgical report found a single overload fracture at the clevis on the piston end of the damper. The certified flight instructor (CFI) did not report any hard landings.