N351SH

The helicopter pilot reported that he was transporting a passenger to a remote drilling site, where a tracked drilling unit was stationed. He reported that he landed into the wind, which necessitated descending over bordering trees into the drilling site. The helicopter touched down on the dirt, and upon lowering the collective, he reported he heard a "bang" and the helicopter slowly started to "pick up a ground wobble." The pilot shutdown the helicopter and both occupants exited without further incident.

A postaccident inspection revealed that the blue and red main rotor blades sustained substantial damage from impacting a black 1.5-inch steel frame attached to the tracked drilling unit, which is used to mount a canvas weather shelter for the drilling crews. The pilot reported that the steel frame was not visible to him from above as he was descending into the drilling site. The pilot further reported that multiple landings have been made to the drilling site in the past 3 months, and that with the previous landings he landed further past the tracked drilling unit and the steel frame was always behind the helicopter.

The pilot reported that there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.

The Federal Aviation Administration Helicopter Flying Handbook (FAA-H-8083-21A, 2012) discusses high and low reconnaissance procedures and states in part:

The purpose of conducting a high reconnaissance is to determine direction and speed of the wind, a touchdown point, suitability of the landing area, approach and departure axes, and obstacles for both the approach and departure.

A low reconnaissance is accomplished during the approach to the landing area. When flying the approach, verify what was observed in the high reconnaissance, and check for anything new that may have been missed at a higher altitude, such as wires and their supporting structures (poles, towers, etc.), slopes, and small crevices.