Incident Overview
On June 22, 2016, at approximately 16:00 local time, the pilot of helicopter HB-ZNZ, an Airbus Helicopters AS 350 B3e (H125) operated by Tarmac Aviation SA, landed on an unmown grass field about 0.5 km northeast of Broglio, Switzerland. The aircraft had transported two workers and their belongings from the Tomeo mountain hut construction site. After landing with rotors running, two flight assistants began unloading material and assisted the workers in disembarking. During these operations, the pilot heard a dull thud from the tail section. Simultaneously, the assistants saw an unidentified object fly away from that area. The pilot then shut down the engine.
Damage Assessment
Inspection revealed damage to one tail rotor blade and an impact mark on the right horizontal stabilizer, corresponding to the tail rotor plane of rotation. A short search found a damaged strip of black plastic fabric on the grass. The fabric had the same surface texture as the marks on the damaged tail rotor and stabilizer.
Conclusion
The investigation concluded that the black plastic fabric strip was presumably sucked into the tail rotor, struck the blade and stabilizer, and was then thrown clear. It was noted that due to the tall grass and dark color of the fabric, it was practically impossible for the pilot and assistants to spot the object during the approach flight. The pilot had made several previous landings at the same site without incident.