Incident Overview
A helicopter operated by an aerial work company completed a preflight inspection without any anomalies before being moved to a landing zone. The helicopter was then equipped with an aerial platform and measuring equipment for planned work near powerlines. After departing the landing zone, the pilot discontinued the aerial work due to atmospheric conditions at the work site and returned to the landing zone.
Personnel Change
A "senior" pilot was consulted and replaced the first pilot. The senior pilot decided to depart and assess the situation from the air. A short time later, the flight returned to the landing zone.
Discovery of Damage
The first pilot performed a "short" postflight examination of the helicopter and noticed that a main rotor blade was substantially damaged. According to the operator, no preimpact mechanical malfunctions or failures with the helicopter were reported that would have precluded normal operation. Additionally, neither pilots nor crew members noticed any abnormal flight characteristics before the damage was discovered.
Investigation Outcome
The investigation was unable to determine which flight caused the substantial damage to the main rotor blade.