What happened
On August 3, 2017, an Airbus AS350 operated by Soloy Helicopters, LLC, was performing a transport flight to a remote drilling site near Delta Junction, Alaska. The pilot was transporting one passenger to the site, where a tracked drilling unit was located.
To land into the wind, the pilot performed a descent over trees bordering the site. After touching down on the dirt, the pilot lowered the collective, at which point a loud bang was heard and the aircraft began to exhibit a ground wobble. The pilot immediately shut down the engine, and both occupants exited the aircraft not injured.
The investigation
Post-accident inspection of N351SH revealed that the blue and red main rotor blades had sustained substantial damage. The damage was caused by an impact with a 1.5-inch black steel frame attached to the drilling unit, which serves as a mount for a canvas weather shelter.
The pilot stated that the steel frame was not visible from above during the descent. The pilot also noted that while several landings had been made at this location over the previous three months, previous approaches had landed further past the drilling unit, leaving the steel frame behind the aircraft.