Accident Details
On May 20, 2017, about 1340 mountain daylight time, a Robinson Helicopter Company R66 helicopter, registration N778TL, impacted terrain following a loss of control on approach to landing near Canon City, Colorado. The commercial pilot and four passengers were not injured, and the helicopter sustained substantial damage. The helicopter was registered to Hynes Aviation Industries, Inc, and operated by Colorado Vertical under Title 14 Code of Federal Regulations Part 91 as a local air tour flight. Day visual meteorological conditions prevailed, and a company visual flight rules flight plan was filed for the local flight. The flight originated from a private helipad near Canon City about 1335.
Flight History
The pilot reported that after completing the local air tour flight, the helicopter approached the private helipad from the south near highway route 50. After crossing route 50 on approach at about 50-60 knots, the pilot began to arrest the descent to view the wind sock and determine the proper approach to the helipad. The pilot reported winds from the south, so he decided to make the final approach from the north. About 200 feet above ground level and west of the helipad, the pilot initiated a left turn, and the helicopter started an uncommanded descent. The pilot applied power to stop the descent, but the helicopter continued sinking towards the terrain. Due to the low altitude, the pilot then committed to land and leveled the helicopter. During the landing, the back of the landing gear skids struck the terrain, resulting in the main rotor blades contacting and severing the tail boom. The helicopter came to rest upright, and the occupants exited.
Postaccident Examination
Postaccident examination of the helicopter airframe and engine revealed no evidence of mechanical malfunctions or failures that would have precluded normal operation. The pilot reported that the helicopter weight was 2,580 lbs at the time of the accident, and the center of gravity was calculated as 92.92 inches.
Video Analysis
A GoPro HERO3 Silver Edition camera was mounted on the helicopter windshield facing inward into the cabin and was used to provide passengers a video of their air tour flight. A copy of the accident flight video was recovered by the operator and provided to the NTSB. The NTSB's Office of Research and Engineering completed a video study to estimate forward and vertical speeds before the hard landing. The analysis was based on a mathematical model of the camera, with yaw, pitch, roll, and horizontal field of view angle estimated from pre-takeoff video frames using reference points visible through helicopter windows and aerial images. According to the study, forward speed was estimated at 34±3 knots, and the highest estimated vertical descent speed was 570±60 ft/min. The helicopter experienced elevated vibrations during an interval of approximately seven seconds that ended just before ground impact.