Fairbanks, AK, USA
N511CC
ROBINSON HELICOPTER COMPANY R44
The pilot was preparing to depart from an asphalt pad at a private airport for a personal flight. The pilot reported that, after he brought the helicopter to hover and proceeded to turn the helicopter while positioned over the pad, a gust of wind "pushed" the helicopter into a snowbank and trees. The helicopter sustained substantial damage. A review of weather information just before and after the time of the accident reported no wind gust conditions and indicated that wind was from 330° at 11 kts before the accident and from 340° at 12 kts after the accident. The pilot reported that there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation. Analysis of postaccident measurements revealed that there was suitable clearance for the helicopter to conduct a hovering turn from where the helicopter was positioned over the pad to the snowbank and trees. It is likely the pilot failed to maintain his position over his reference point during the hovering turn along with not compensating for the wind conditions, which resulted in a loss of control in flight and impact with the snowbank and trees.
HISTORY OF FLIGHTOn April 19, 2018, about 1600 Alaska daylight time, a tundra/snow board-equipped Robinson R44 Raven II helicopter, N511CC, impacted trees and a snowbank while conducting a hover turn at the Chena Marina Airport (AK28), Fairbanks, Alaska. The private pilot, the sole occupant, sustained no injury and the helicopter sustained substantial damage. The helicopter was registered to Godspeed Leasing, LLC, and was operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a visual flight rules personal flight. Day visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The helicopter lifted off from the helicopter landing pad about 1600. The helicopter was stationed on an unmarked asphalt pad surrounded by gravel. The pad was connected to private hangar where the helicopter was kept inside. The pilot reported the purpose of the flight was to fly to a remote cabin. Prior to bringing the helicopter to a hover, he received the automatic terminal information system (commonly known as "ATIS") information from the Fairbanks International Airport (FAI), Fairbanks, Alaska. The pilot, stationed in the right seat, picked up the helicopter from the pad, to about a 10-ft above ground level hover profile. The pilot then executed a hovering turn to the south, with the intent of facing the east. He reported that as the helicopter was turning, a gust of wind from the northeast "pushed" the helicopter into the trees. The main rotor blades impacted various spruce and birch trees and the helicopter subsequently impacted a snowbank near the trees and the ground. The pilot was able to egress from the helicopter without further incident. Two Federal Aviation Administration (FAA) aviation safety inspectors from the Fairbanks Flight Standards District Office responded to the accident site on the day of the accident to interview the pilot, photograph the wreckage, and measure the dimensions of the pad and the surrounding area as shown below in figure 1. The pad was about 10 ft wide by 45 ft long. The distance from the center of the pad to the snowbank, was about 40 ft, and to the trees it was about 44 ft. Figure 1 – View of the pad at AK28, along with the snowbank and trees (courtesy of the FAA). The pilot reported that there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation. AIRCRAFT INFORMATIONThe Robinson R-44 II Pilot's Operating Handbook (POH) states that for the main rotor system, the radius is 16.5 ft and the diameter is 33 ft. The POH further states that from the front of the fuselage to the end of the tail rotor system guard, the length is 29.41 ft. METEOROLOGICAL INFORMATIONATIS information Romeo, from FAI at 1553 (2353 Zulu), stated the wind direction originated from 330° at 11 kts. ATIS information Sierra, from FAI at 1653 (0053 Zulu), stated the wind direction originated from 340° at 12 kts. There were no reports of any wind gusts in the ATIS information. FAI is at an elevation of 439 ft above mean sea level and is about 1 mile east of AK28. AIRPORT INFORMATIONThe Robinson R-44 II Pilot's Operating Handbook (POH) states that for the main rotor system, the radius is 16.5 ft and the diameter is 33 ft. The POH further states that from the front of the fuselage to the end of the tail rotor system guard, the length is 29.41 ft. WRECKAGE AND IMPACT INFORMATIONThe helicopter sustained substantial damage to the main rotor system, the fuselage, the tail boom, and the tail rotor system as shown below in figure 2. Figure 2 – View of the recovered helicopter with substantial damage (courtesy of the FAA). ADDITIONAL INFORMATIONHovering Turns The FAA Helicopter Flying Handbook FAA-H-8083-21 discusses hovering and hovering turns. This document discusses wind compensation during hovering and states in part: Pilots direct the thrust of the rotor system by using the cyclic to change the tip-path plane as compared to the visible horizon to induce travel or compensate for the wind and hold a position. This document discusses how a hovering turn should be conducted and states in part: A hovering turn is a maneuver performed at hovering altitude in which the nose of the helicopter is rotated either left or right while maintaining position over a reference point on the surface. Hovering turns can also be made around the mast or tail of the aircraft. The maneuver requires the coordination of all flight controls and demands precise control near the surface. A pilot should maintain a constant altitude, rate of turn, and rpm. This document also states common errors during a hovering turn and states in part: Failing to maintain position over the reference point. Wind Conditions Near Buildings FAA Technical Report FAA/RD-84/25, Evaluating Wind Flow around Buildings on Heliport Placement, addresses the wind's effect on helicopter operations near buildings. This document discusses pilot experience with assessing wind conditions and states in part: Pilots become knowledgeable of what winds may be expected about a building or heliport facility through familiarity with varying wind conditions.
The pilot's failure to maintain helicopter control while in a hovering turn, which resulted in a collision with obstacles.
Source: NTSB Aviation Accident Database
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