N20620

HISTORY OF FLIGHTOn February 18, 2013, at 1424 Pacific standard time, a Bell 206B helicopter, N20620, collided with power transmission lines near Eureka, Nevada. El Aero Services, Inc., owned the helicopter, which was being operated by the Bureau of Land Management (BLM), U.S. Department of the Interior (DOI), as a public-use seed-dispersal flight. The commercial pilot sustained fatal injuries; the helicopter was substantially damaged during the accident sequence. The flight departed about 1420 from a temporary loading area 2 miles east of the accident site. Visual meteorological conditions prevailed, and no flight plan had been filed.

The helicopter was utilized for a low-level (100-200 feet above ground level) aerial reseeding project for the area damaged by the "Pinto Fire," which occurred in June 2012, just east of Eureka. The land was managed by the BLM, and the services of El Aero were retained for the DOI utilizing an "On Call" contract.

At 0700 on the morning of the accident, the pilot departed in the helicopter from Ely Airport (Yelland Field), Ely, Nevada. He proceeded 40 miles south-southwest to a helispot south of Lund, at the base of Ninemile Mountain. Over the course of the next 2 hours he performed about 10 separate seed application runs utilizing a seeder attached to the bottom of the helicopter, returning to the helispot to reload each time. At 0947, he departed for a second helispot 70 miles northwest in the Pinto Creek Ranch area, along the eastern foothills of the Diamond Mountains range. From there he flew a reconnaissance mission along the intended drop zone with the BLM Helicopter Manager. The manager stated that during the flight he made the pilot aware of two separate sets of power transmission lines in and around the seeding area. The pilot had experience flying in that area before, and informed the manager that there was in fact a third set of power lines in the seeding area.

The pilot then performed multiple uneventful seed-dispersal runs throughout the morning. The operation continued after lunch, however, after departing for the last drop of the day, he did not return. A search was initiated, and at 1500 the helicopter wreckage was located. PERSONNEL INFORMATIONThe 74-year-old pilot held a commercial pilot certificate with ratings for airplane single and multi-engine land, rotorcraft-helicopter, and instrument airplane. He additionally held a flight instructor rating for airplane single and multi-engine, and rotorcraft-helicopter, as well as an airframe and powerplant mechanic certificate with inspection authorization. Due to a history of diabetes he held an aviation medical examiner assisted special issuance (AASI) second-class medical certificate issued in April 2012, with limitations that he must wear lenses for near and distant vision. At the time of application for the medical certificate, he reported a total flight experience of 37,500 flight hours. His most recent airman competency/proficiency check was performed on April 26, 2012.

The pilot was involved in another helicopter accident, which occurred while herding horses on October 18, 2007, in Medora, North Dakota. The NTSB determined the probable cause of the accident as, "The pilot failed to maintain clearance from the fence while maneuvering at a low altitude". See NTSB accident number CHI08CA021 for further details. AIRCRAFT INFORMATIONThe helicopter was manufactured in 1981 and equipped with a Rolls-Royce/Allison 250-C20B gas turbine engine.

A review of the maintenance logbooks revealed that the last inspection was for a 100-hour engine and airframe exam dated February 8, 2013. At that time the airframe had accumulated a total flight time of 15,540 hours, with the engine accruing 1,492.8 hours since major overhaul.

The helicopter was equipped with a seed spreading system, the operation of which was controlled by the pilot in conjunction with the onboard agricultural navigation system. The seeder consisted of a bucket and dispersal mechanism, and was attached to the helicopter's belly hook. The lowest portion of the seeder was about 11 feet below the skids. The helicopter was not equipped with a wire strike protection system, nor was it required to be under the terms of the DOI contract. METEOROLOGICAL INFORMATIONAn automated surface weather observation at Eureka Airport (elevation 5,958 feet msl, 12 miles northwest of the accident site) was issued at 1415. It indicated calm wind; clear skies, with visibilities of 10 miles; temperature of 7 degrees C; dew point -8 degrees C; and an altimeter setting at 29.91 inches of mercury.

According to the U.S. Naval Observatory, Astronomical Applications Department, the altitude of the Sun when viewed from Ely at 1425 would have been 28.4 degrees, with an Azimuth (E of N) of 223.2 degrees. AIRPORT INFORMATIONThe helicopter was manufactured in 1981 and equipped with a Rolls-Royce/Allison 250-C20B gas turbine engine.

A review of the maintenance logbooks revealed that the last inspection was for a 100-hour engine and airframe exam dated February 8, 2013. At that time the airframe had accumulated a total flight time of 15,540 hours, with the engine accruing 1,492.8 hours since major overhaul.

The helicopter was equipped with a seed spreading system, the operation of which was controlled by the pilot in conjunction with the onboard agricultural navigation system. The seeder consisted of a bucket and dispersal mechanism, and was attached to the helicopter's belly hook. The lowest portion of the seeder was about 11 feet below the skids. The helicopter was not equipped with a wire strike protection system, nor was it required to be under the terms of the DOI contract. WRECKAGE AND IMPACT INFORMATIONThe general area of the accident site was snow covered, and comprised of rolling hills intermittently dispersed with burnt trees. The terrain immediately to the west rose to a peak about 300 feet above the accident site.

The entire helicopter, with the exception of the main rotor blades, was located about 475 feet north of a set of power transmission lines, at an elevation of about 6,700 feet mean sea level (msl). The lines traversed from east to west, climbing about 300 feet with the terrain. The lines consisted of three sets of horizontally positioned tandem power cables. Above the power cables were two thinner-gauge static lines; the southern static line was severed, and was found draped over the power cables. The seeder was half full with seeds, and was located about 10 feet from the helicopter. The intermediate area was covered with a layer of seeds. Both main rotor blades remained attached to the mast head, and had come to rest to the south, midway between the power lines and helicopter.

The helicopter sustained crush damage from the nose through to the aft bulkhead, and the tailboom was severed just forward of the horizontal stabilizer. The outboard sections of both main rotor blades exhibited serrated gouges, with upper and lower skin striations consistent in appearance with the severed static line. Similar patterns were present on the main rotor mast. The seeder exhibited a similar gouge in its upper skin, with horizontal scratches and black sooting on the forward surface of its bucket, about 5 feet below the helicopter skids. ADDITIONAL INFORMATIONPilot Itinerary

The pilot began the seeding mission on the morning of February 13, when he departed from his home airport in Elko, Nevada, in the accident helicopter. For the next 4 days, he accumulated about 8 hours of flight per day, totaling 33.9 hours. On the day of the accident he accumulated 6.6 hours of flight time, and as such his 5-day total for the period leading up to the accident was 40.5 hours.

Examination of the pilot's flight history for the prior 2 months revealed 6-day flight time totals of between 8 and 28.4 flight hours.

The helicopter fuel truck driver had been working with the pilot all week for the seeding operations. They had shared a hotel room each evening in order to reduce expenses. On the night prior to the accident, the pilot went to bed at 2030 and awoke at 0530. He was not aware of the pilot waking up or having sleeping problems during the night. He stated that he had shared rooms with the pilot on prior missions and that nothing about that evening stood out as unusual.

Pilot Fatigue Issues

With regards to the effect of time-on-task as a cause of fatigue and an influence on performance among helicopter pilots, one such study (A.M. Stave, "The Effects of Cockpit Environment on Long-Term Pilot Performance," Human Factors, Vol. 19 (1977)), examined the effect of a helicopter cockpit environment and continuous flying activity on subjective fatigue and pilot performance. For this study, flight legs were designed to simulate repetitive circular, helicopter air taxi flights conducted under instrument flight rules in a metropolitan area, with complete circuits lasting about 1 hour and including three approaches and landings. Pilots flew for flight periods varying between 3 and 8 hours, with rest breaks permitted during the 4- and 8-hour flight periods. Pilot performance was measured, and the pilots also provided ratings of subjective fatigue each hour.

Time-on-task and subjective fatigue were found to have no effect on some basic aspects of flying performance, but they were associated with increased "lapses" in performance, such as navigational errors. The study found that subjective fatigue increased with time-on-task, peaking during the last hour of flight, but scheduled breaks delayed the onset of subjective fatigue.

Flight Time and Duty Period Limitations

The DOI contract specified limits for the pilot, which capped flight time during any assigned duty period to 8 hours. Thirty-six or more flight hours in a consecutive 6-day period required the next calendar day off duty, with a maximum of 42 hours in any consecutive 6-day period. These flight limitations exceeded those required under the rules ...