Incident Overview
A pilot conducting an external load operation to pour concrete for a new ski lift experienced a sudden mechanical failure. The pilot reported hearing a loud 'bang' noise, followed by a growling sound, and the aircraft's nose attempted to turn right. In response, the pilot entered autorotation.
Landing and Damage
The aircraft landed hard on upsloping terrain, causing the landing skid to collapse. No other damage was explicitly noted in the pilot's report or subsequent examination.
Mechanical Examination
Post-accident inspection of the aircraft revealed a fracture failure of the tail rotor drive system intermediate gear box, specifically at 42 degrees. The nature of the failure and its connection to the reported noises and handling characteristics were identified during examination.
Operational Context
The flight was part of an external load operation using buckets to pour concrete for a new ski lift. No further details regarding the aircraft type, registration, operator, location, date, or time of day were provided in the source.