N4361R

On November 7, 2024, about 0837 Pacific standard time, a Robinson Helicopter Company R44 II, N4361R, was substantially damaged when it was involved in an accident near Durkee, Oregon. The pilot was not injured. The helicopter was operated as a Title 14 Code of Federal Regulations Part 133 external load flight.

The pilot reported that, after picking up the first sling load from a staging area using a 50-ft long line, he conducted a power check that “was fine.” He then departed for the mountain camp site. Upon arrival, he approached slowly to reassess power and wind conditions and determined that all checks were normal. He proceeded to the drop-off site in a slow walking pace with about a 5-ft-per-minute rate of descent. The pilot had his head out of the cockpit watching the load when he realized that “the helicopter was losing considerable lift,” accompanied by the sound of the blades whooshing. He did not hear the low rotor rpm horn, but it was obvious to him that the helicopter was not performing as expected. He immediately released the load and entered an autorotation. He saw the two ground members run to the center of the clearing, so he maneuvered to the only feasible landing spot, a sloped area between juniper trees.Before touchdown, the main rotor blades struck a tree, the right skid contacted the ground, and the helicopter rolled onto its right side, which resulted in substantial damage to the fuselage, tail cone, empennage, and the main rotor assembly. The pilot exited the helicopter with the assistance of one of the two witnesses.

According to two hunters located at the drop site, when they heard the helicopter approaching, they walked to the drop-off site. One hunter reported that, when the helicopter approached the drop-off site, nothing appeared different than what he had seen on previous hunts with helicopter support from the same company. He said the net came down slowly at first until about 10 ft above the ground, then fast enough to be alarming. The other hunter reported that the helicopter was supposed to hover while they removed items from the net. He looked up and saw that the net was coming down fast. Both hunters saw the shackle from underneath the helicopter falling as the long line was released from the helicopter, and ran from the falling net. Only one hunter saw the helicopter slowly descend and hit the hillside.

According to a hunter at the trailhead, they had split the gear into two loads. In the past they weighed the gear, but this time they estimated the weight. The first load consisted of coolers, drinks, a stove, a chainsaw, and propane. The hunter recalled that when the pilot lifted the first load, he could not take off. He landed and they removed some of the gear. The pilot then lifted the load and departed. The hunter learned later that the helicopter had crashed. According to the two hunters that were at the drop site, they try to keep the loads less than 600 lbs.

The pilot estimated that the accident site was located about 5,300 ft mean sea level (msl). The density altitude at the time was about 4,500 ft, the wind was about 3 knots “off the nose” of the helicopter, and the temperature was about -1°C. The terrain in the vicinity of the accident was hilly and uneven.

Baker City Municipal Airport (BKE) Baker, Oregon, about 26 miles northwest of the accident site at an elevation of 3,373 ft msl, reported weather as wind calm, visibility 10 statute miles, visibility clear, temperature 1°C, dew point temperature -4°C, with a barometric pressure of 30.39 inches of mercury around the time of the accident.

Postaccident examination of the helicopter revealed a fractured windscreen, damage to the left side of the fuselage, large dents and tears to the sheet metal underneath the left side rear door, and bent framework. The tail cone exhibited bending and large dents to the sheet metal and bent structural metal under the skin. The empennage exhibited substantial damage to the lower vertical and horizontal stabilizers. The two main rotor blades exhibited large upward bending signatures along with chordwise creases, consistent with excessive upward coning.

Examination of the engine revealed dents to the exhaust system, normal appearance of the spark plugs, and oil pooled in the fuel servo venturi, but no damage that would preclude a test run. Test runs of the engine resulted in normal operation at a higher-than-idle speed that was attributed to damage interference with the throttle assembly. A check of the magnetos revealed normal engine speed reductions that could not be quantified due to an inoperative engine tachometer. The examination and test run identified no preaccident mechanical malfunctions or failures that would have precluded normal operation.

The pilot estimated the weight of the helicopter at the time of the accident to be about 2,450 lbs, 50 lbs less than its maximum gross weight. Performance calculations revealed that, at 2,450 lbs, along with the estimated environmental conditions of the accident site, the helicopter was capable of a hover OGE up to 5,800 ft msl. The helicopter’s chart for hover OGE performance also showed that engine performance is reduced at gross weights above 2,480 lbs. The chart showed that a helicopter that, at 2,500 lbs gross weight under the same environmental conditions, the helicopter could hover OGE up to 5,300 ft msl (see figure 1).

Figure 1. Out of ground effect hover chart for the R44 II helicopter, showing OGE hover capability for 2,450 pounds (blue arrows) and 2,500 pounds (orange arrows).

According to the Federal Aviation Administration’s Helicopter Flying Handbook (FAA-H-8083-21B), an OGE hover is defined as “Hovering a distance greater than one disk diameter above the surface. Because induced drag is greater while hovering out of ground effect, it takes more power to achieve a hover out of ground effect.”

According to the R44 II Pilot’s Operating Handbook, the main rotor diameter is 33 ft.