WPR10FA012

The pilot's failure to maintain clearance from a power pole to which he was connecting wire-pulling ropes.

The pilot of the helicopter was pulling a rope along a line of wood power poles, and placing the rope within the lowest traveler (pulley) attached to each power pole. The placement of the rope into the traveler required maneuvering the helicopter in close proximity to the pole, while the rope was attached to a long-line that was shorter than the distance from the top of the pole to the traveler that the rope was being placed in. The pilot had already placed the rope in the traveler on the first pole of the line, and had just completed the placement of the rope into the traveler on the second pole, when he began to maneuver the helicopter in order to proceed to the next pole. At the beginning of that maneuver, the pilot inadvertently allowed the helicopter to come close enough to the pole that he had just finished working on for its main rotor blades to come in contact with the pole. Immediately thereafter, all five of the main rotor blades separated from the helicopter, whereupon the helicopter's tail boom separated from its fuselage. The helicopter then fell to the down-sloping terrain near the base of the pole. No pre-accident anomalies were found with the helicopter's airframe, engine, or flight control system.

HISTORY OF FLIGHT On October 12, 2009, about 0850 Pacific daylight time, a McDonnell-Douglas 369FF helicopter, N527SH, collided with a wood power pole about 18 miles southeast of Fossil, Oregon. The commercial pilot, who was the sole occupant, was killed in the accident, and the helicopter, which was owned and operated by Pacific Rim Helicopters LLC, sustained substantial damage to most of its structure. The 14 Code of Federal Regulations Part 133 external load long-line flight was being operated in visual meteorological conditions. The pilot's initial point of departure was Spray, Oregon, but he subsequently refueled the helicopter at a remote landing site, and then had been airborne again for about 20 minutes when the accident occurred. No flight plan had been filed. According to witnesses, on the morning of the accident the pilot flew in support of installing travelers/pulleys on the wood power poles, so that later ropes could be pulled through these travelers. The plan was that once all the ropes were in place on the travelers, then they would be used by ground crews to pull power lines into place on the poles. After assisting with the traveler installation from about 0700 to about 0815, the pilot landed and refueled the helicopter. He then took off again, and began to string the ropes through the travelers around 0830. The poles the rope was being connected to were between 400 feet and 500 feet apart. The rope that was being pulled at the time of the accident was being placed in the lowest traveler on the pole, which was located 32.4 feet from the top of the pole. This traveler was connected directly to the pole, not on an extended cross-arm (see Image 6). The pilot had already placed the rope in the traveler on the first pole of the run, and had just finished placing the rope in the traveler of the second pole when the accident occurred. There were a number of witnesses that heard the helicopter's main rotor blades come in contact with the power pole, but only one of them was looking at the helicopter at the moment it contacted the pole. Upon hearing the sound of the blade impact, all of the witnesses immediately looked toward the helicopter in time to see the remaining main rotor blades impacting the pole. The one witness that was looking directly at the helicopter as its main rotor blades initially came in contact with the pole had been watching the helicopter from the time it first approached the area around the pole. All the witnesses reported that they could see the rotor blades separating from the helicopter as each blade impacted the pole, and that immediately thereafter the helicopter rolled slightly to the right and fell to the ground. They also all agreed that the winds were calm at the time of the impact. The closest witness was about 120 to 140 feet away from the helicopter. He had been holding onto the 5/16th inch diameter rope in order to provide some degree of tension on it. This added tension kept the rope from moving around, and helped the pilot pull the rope through the gates on the travelers. According to this witness, the rope had just clicked past the gate on the traveler, and the pilot appeared to turn his head to look toward the pole that he was going to go next. The pilot then looked back at the pole where he had just placed the rope, and then he appeared to look down at the mirror on his skid; which had been placed there to allow him to observe the area aft of the helicopter. It appeared to the witness that the pilot was just then starting to maneuver away from the pole, so he turned away from the helicopter in order to walk over to his truck so that he could make radio contact with the pilot on the truck-based radio as the pilot moved to the next pole. At that time the witness estimated that the helicopter fuselage was about 30 feet laterally from the pole, and that the bottom of the helicopter was about 10 feet higher than the pole. About three to five seconds after he turned away, he heard what he described as a loud impact noise, whereupon he quickly turned his head back toward the helicopter. As he did so, he saw the helicopter's main rotor blades hitting the pole and coming off the helicopter one at a time. He said that he could clearly hear each blade hit the pole. According to this witness, he did not hear any unusual noises before he heard what he believed was the sound of the first rotor blade coming in contact with the pole. He said that prior to when the first blade impacted the pole, the sounds coming from the engine appeared normal. He reported that he did not hear any popping, coughing, or rpm change coming from the engine prior to the impact. He said that what he did hear was what he thought was the engine rpm beginning to wind down after all the blades impacted the pole. This witness further stated that when he first looked back at the helicopter after hearing the first impact noise, the long-line that was pulling the rope was still attached to the helicopter. He said that he was aware that after the accident the long-line was found released from the helicopter and laying next to it, but he said he did see it at the moment of release. Another witness was about 800 to 900 feet away, helping to get travelers set up on the power poles further down the line that the helicopter was working. He momentarily paused from what he was doing, and looked back at the helicopter just as it was laying the rope onto the traveler gate. He then saw the helicopter descend, and watched as the downward force created by the descent pulled the rope past the traveler gate. He then saw the helicopter climb back up a few feet, so he went back to what he was doing because he assumed the pilot was then starting to move on to the next pole. Soon after he turned away, he heard a "funny sound," that he described as kind of a "woosh." He then quickly looked back toward the helicopter, which was already making contact with the pole. Almost immediately thereafter the helicopter fell to the ground. This witness said that he did not notice any change in the sound of the engine rpm, nor did he hear any loud pops or bangs prior to hearing the "woosh" sound. He also said that he felt that only about one second had elapsed between the time he heard the "woosh" and when he was looking directly at the helicopter; which was already in contact with the pole. A third witness was about 800 to 900 feet away at the spool from which the rope was being fed out. He was responsible for making sure that there were no snags as the rope unwound from the spool, and to operate the spool clutch if necessary (which it was not during this operation). Since his primary focus was on the spool, he only occasionally looked at the helicopter. He was not looking at the helicopter at the moment that it came in contact with the pole, but he did hear a loud "bang or pop." He therefore looked very quickly toward the helicopter, whereupon he saw that it was already in contact with the pole, and its blades were coming off. He had not heard any unusual noises prior to the loud bang or pop, and he did not notice whether the long line was still attached or not. A fourth witness was about 800 feet away from the pole, and was positioned on a paved road to stop any traffic that approached during that part of the pull operation. This witness said that he was watching the helicopter almost the whole time. He watched the pilot place the rope onto the traveler on the first pole of the run, and then watched him as he moved on to the second pole. Because the pole was in a direct line between the witness and the helicopter, the witness could not tell what the lateral distance was between the helicopter and the pole. He said that the helicopter was only slightly above the top of the pole, but that his position was no different than at other poles he had seen him work near. From the distance he was at, he could not tell when the rope went into the trav