Aviation Accident Summaries

Aviation Accident Summary SEA02TA067

Richland, WA, USA

Aircraft #1

N8353F

Hughes 369D

Analysis

During an aerial animal capture flight, the helicopter was positioned about 15 feet above ground level over the elk for capture. The pilot positioned the helicopter to get the gunner into firing position and told the gunner to get ready. When ready, the gunner fired the net. Immediately after the shot, a loud bang was heard and the helicopter began to vibrate. The pilot landed the helicopter without further incident. After the main rotor blades stopped turning, it was noted that one of the blades had a hole on the leading edge that exposed the spar. Additional holes were noted on the back of the blade about two inches from the trailing edge. The net that was discharged was examined. It was noted that one of the net weights from one of the four corners was missing and had separated from the attaching material. The weight was later found about 300 feet from the net and displayed impact damage and was slightly bent.

Factual Information

On April 11, 2002, approximately 1230 Pacific daylight time, a Hughes 369D, N8353F, registered to Hawkins & Powers Aviation, operated by the United States Fish and Wildlife as a Public Use aerial animal capture operation, was substantially damaged when a weight from the net separated and contacted a main rotor blade. The operation was being conducted about seven miles north of Richland, Washington. Visual meteorological conditions prevailed at the time and no flight plan was filed. The commercial pilot, the gunner (net gun shooter) and two muggers (animal capture ground support) were not injured. The flight had been operating in the area since 0545 the morning of the accident. The pilot reported that the mornings activities of capturing the animals was going well and the crew was working efficiently. The pilot stated that they moved into a new area and found a group of elk. An elk was chosen for capture and the pilot approached that animal between 20 and 25 miles-per-hour and about 15 feet above ground. The pilot crabbed the helicopter to get the gunner into firing position. The pilot told the gunner to get ready and the gunner positioned himself out the door. The helicopter came across the animal and the gunner fired the net. The pilot reported that he heard the gun go off, then immediately heard a second bang. The helicopter started to vibrate and the pilot landed the helicopter without further incident. After the main rotor blades stopped turning, the pilot noticed the damage to one of the blades. The pilot found where the net had landed and noted that there was a missing weight which broke where the weight is attached to the net. The net was on the ground in full deployment as a normal shot would be. The pilot deducted that the weight came off as the net was fired. The mugger sitting in the front right seat, who is also a mechanic, reported that about 18 inches in from the blade tip on the leading edge, a hole was visible that exposed the spar. It appeared that the weight flipped over and hit the blade in the bottom putting a hole in the back of the blade about two inches from the trailing edge. The other mugger sitting in the right rear seat reported that he was looking over the gunners shoulder when the shot was made. He reported that almost instantly after hearing the report of the gun he heard a loud bang followed by the helicopter shaking. The pilot immediately landed the helicopter. The gunner reported that he was sitting in the left rear seat behind the pilot and was in direct communication with the pilot (hot mike) during the operation. After the gunner shoots an elk, the helicopter either lands or does a short hover-exit so that the muggers can jump out and subdue the animal and prepare it for transport. The gunner stated that he was in a harness which allows him to lean out of the door to aim over the animal thus avoiding the landing skids and the main rotor blades. The gunner stated that he was leaning out like he normally does to make the shot. The net deployed normally (straight out like it should) then there was a "bang" and the helicopter started to vibrate. The pilot then landed the helicopter. The gunner further stated that "it seemed like one side of the net wasn't deploying the way that it normally would have." The gunner assumed it was because of the missing weight from one of the corners. When the net is discharged, the weights (4) come out of the barrel, and the net rotates about 180 degrees. After the net is discharged, it is gathered up and taken back to the landing base for inspection, repair if needed, and repacking in the canister. There is no life limit for the netting material. The weights are checked for nicks or burrs that could hamper discharge from the barrel. The separated weight was located about 300 feet from where the net came to rest. The weight displayed impact damage and was bent slightly.

Probable Cause and Findings

Failure of the netting material securing a net weight while maneuvering. The net weight was a factor.

 

Source: NTSB Aviation Accident Database

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