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N400MB accident description

Vermont map... Vermont list
Crash location 42.997500°N, 72.620834°W
Nearest city Newfane, VT
42.965080°N, 72.700649°W
4.6 miles away
Tail number N400MB
Accident date 21 Apr 2010
Aircraft type Mcdonnell Douglas Helicopter 369E
Additional details: None

NTSB Factual Report


On April 21, 2010, about 1101 eastern daylight time, a McDonnell Douglas 369E, N400MB, registered to and operated by Air 2 LLC, impacted with a "pulling" rope and crashed near Newfane, Vermont. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 Code of Federal Regulations (CFR) Part 133 rotorcraft external load flight. The helicopter sustained substantial damage. The commercial certificated pilot and one additional crewmember sustained serious injuries. The flight originated about 16 minutes earlier from a landing zone near the accident site.

According to the aircraft operator, installation of 54 miles of 345 kV transmission lines was being performed parallel to existing 345 kV transmission lines between Vernon and Cavendish, Vermont. The installation was being supported in part by personnel and equipment from Air 2 LLC, and Cianbro Corporation. The purpose of the accident flight was for the additional crewmember of Air 2 LLC to install a hold down block (X100 Block) onto a white colored "pulling" rope that was connected between transmission structures Nos. 141 and 163. The X100 Block was to be installed on the south side of structure 144, and is used to facilitate installation of transmission lines. The pulling rope connects to a solid diameter wire which is attached to the conductor wire intended to be installed.

The pilot stated that on the day of the accident earlier that morning, he checked the weather and visual flight rules (VFR) conditions were forecast to exist in the area. He performed a pre-flight on the helicopter, and did not find any discrepancies. He started the engine and departed from Springfield, Vermont, and flew to landing zone (LZ)-11, where he landed about 0715. While there he, “…Had daily tailboard meeting. Setup to hang fiber blocks, glass conductors, and blocks….” Later that morning he flew Air 2 LLC employees to structure No. 166 for installation of equipment. He was then requested to install additional equipment (hold-down) block at structure No. 144. He brought back two employees of Air 2 LLC to LZ-11 and dropped them off, then flew to structure No. 166, where he picked up the remaining Air 2 LLC employee and flew to structure No. 144. Cianbro Corporation personnel advised they needed the hold down on the North side of the pole. When he arrived at the structure, they contacted Cianbro Corporation personnel to confirm what side for placement of the equipment (South side), and then called personnel from Air 2 LLC located at LZ-7 asking if the pull had been stopped. Personnel from Air 2 LLC contacted personnel from Cianbro Corporation and was informed that the pull had been stopped and the helicopter was clear to proceed.

The project manager for Cianbro Corporation later reported that the all stop command was given on a citizens band (CB) radio transceiver approximately 3 to 5 minutes before the time of the accident, and several company employees confirmed that there was no pulling occurring at the time of the accident. One employee reported that at the time of the accident, there was no movement of the running board.

The pilot further reported that personnel from Air 2 LLC relayed the response from Cianbro Corporation to him that the pull was stopped and he could precede. After confirming that the pull was stopped, he began to setup for his approach. He made notice of the trees on the right of way border and the weather, which consisted of clear skies and light and variable wind from 0 to 5 miles-per-hour with no gusts. He hovered high above the proposed work site to check aircraft power and determined there was adequate power, and confirmed the lineman in the helicopter was ready. He began his approach towards the structure and slowly hovered down and determined he had plenty of room to do the work. He positioned the helicopter approximately 50 ft. from the pole and started to slowly approach the rope to a position where it would be level with the floor of the helicopter. When the helicopter was close enough, the lineman installed the X100 Block (hold-down block).

The additional crewmember stated that he had installed the hold down block on the pulling rope, and was in the process of getting ready to drop the rope (attached to the hold down block) to the ground, when he saw a wave on the pulling rope coming from structure 144; this wave in the rope did not contact the helicopter. A short time later he saw a second wave approaching that was obviously going to contact the main rotors. He jumped into the aft cargo area and was completely inside the aft cargo compartment.

After completion of installation of the hold-down block, the pilot reported he slowly started backing away, making sure to keep the block and the floor of the helicopter level and even. When he was almost adequate distance away from the X100 Block to start climbing out of the work area, he felt something hit the helicopter. After the initial impact he felt 3 to 4 tugs and the helicopter began descending. He attempted to make an emergency landing. The next thing he remembers was being out of the helicopter walking around trying to figure out what had just happened. Following ground contact, the additional crewmember was ejected from the helicopter and landed on his entire left side of his body.

According to a nearby witness, he observed the helicopter hovering near structure No. 144, and then heard a pop followed by seeing the helicopter descending to the ground.


The pilot, age 56, holds private and commercial pilot certificates with rotorcraft helicopter and instrument helicopter ratings at the commercial level, and was last issued a second class medical certificate issued April 12, 2010, with a limitation to wear corrective lenses.

The Pilot/Operator Aircraft Accident/Incident Report submitted by the operator indicated the pilot’s total time was 16,420 hours, of which 15,180 hours were in rotorcraft type aircraft and 8,000 were in the accident make and model helicopter.

The pilot was admitted to a hospital on the day of the accident, and was released from the same hospital on April 26, 2010.


The helicopter was manufactured in 1990 by McDonnell Douglas Helicopter Company as model 369E, and was designated serial number 0420E. It was powered by a Rolls-Royce Corporation (formerly Allison Engine Company) 250-C20R/2 turboshaft engine.

Review of the maintenance records revealed the helicopter was last inspected in accordance with a 100-Hour inspection on April 14, 2010; the helicopter total time at that time was 2,673.8 hours. The helicopter total time at the time of the accident was 2,688.2 hours.


A surface observation weather report taken at Dillant-Hopkins Airport (EEN), Keene, New Hampshire, at 1055, or approximately 6 minutes before the accident indicates the wind was from 220 degrees at 5 knots, the visibility was 10 statute miles, and clear skies existed. The temperature and dew point were 17 and 3 degrees Celsius, respectively, and the altimeter setting was 29.82 inches of Mercury. The accident site was located approximately 17 nautical miles and 290 degrees from EEN.


The communication for the all stop which was broadcast using a CB radio transceiver was not recorded.


The project manager of the company that was installing the transmission lines (Cianbro Corporation) reported that when he arrived at the accident site, he noted that the "pulling" rope was broken between structure Nos. 143 and 144. The "pulling" rope found wrapped around the main rotor mast remained connected to structure No. 143, which was continuous to structure No. 141. The other end of the broken "pulling" rope was secured to structure No. 144, and was continuous to structure No. 163. He also stated that following the accident but before his arrival, ground personnel secured the broken "pulling" rope to structure No. 144.

Examination of the accident site by an FAA inspector revealed the helicopter came to rest on its left side nearly inverted. Two of the five main rotor blades were fractured but found in close proximity to the resting point of the helicopter. A white colored rope was wrapped around the main rotor static mast below the swash plate.

The operator reported that there was no helicopter preimpact mechanical failure or malfunction. The operator also reported that their postaccident examination of the accident site and surrounding area revealed “…evidence of structure movement North of the crash site at structure…” 157, as evidenced by numerous fresh tracks in the ground near the structure, fresh backfill on the left and right poles of structure No. 157, and fresh seeping creosote at ground level of one of the poles.


According to personnel associated with the installation of the power-lines, re-plumbing of structure No. 157 was initiated and completed on April 19, 2010. The job involved the use of an excavation bucket, and other equipment.

Personnel of the operator reported that a rope inside the cabin area planned to be utilized by the additional crewmember was physically different than the "pulling" rope that was found wrapped around the main rotor mast.

Postaccident, the operator of the helicopter evaluated their procedures and implemented changes including:

1) AIR2 edited it's safe work procedures on helicopter use during wire stringing operations.

2) While the conductor or pulling line is being pulled or in motion by a power driven device, employees are not permitted directly beneath overhead operations or on the structure except as necessary to guide the stringing sock or board over or through the stringing sheave.

3) During all active wire stringing operations, the helicopter shall maintain a distance that will allow for obstruction clearance between the helicopter and the structures including all stringing equipment, ropes, hard lines and conductors.

4) In the event that it becomes necessary to use the helicopter to perform work or adjust equipment to facilitate the stringing operations, all wire movement, rope movement, and work within the segment must stop. The work with the helicopter can proceed only after the following has occurred:

a) Three-way communications must be established between the person in charge of the wire pulling operation and the pilot confirming that all work has stopped.

b) b) The pilot must perform an aerial reconnaissance of the entire segment to visually confirm the verbal statement of the person in charge that the pull is in an "ALL STOP", and that there are no other work activities or problems in that segment.

c) Once these tasks are completed, the pilot can proceed with the work activity. Upon completion of the work activity, the pilot will communicate to the person in charge when the helicopter is in the clear and it is safe to resume pulling.

NTSB Probable Cause

The pilot's inadvertent encounter with a rope while maneuvering during powerline operations for undetermined reasons.

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