History of Flight
On December 15, 2012, at about 1005 Alaska standard time, a Eurocopter AS350-B3 helicopter, Canadian registration C-GYPH, crashed in an area of tall trees near Beluga, Alaska. The helicopter was being operated by Prism Helicopters, Inc., of Wasilla, Alaska, under 14 CFR Part 133 for an external load flight supporting a geophysical survey project. Visual meteorological conditions prevailed, and company flight following procedures were in effect. The pilot, the sole occupant, sustained serious injuries. The flight originated at a remote survey site about 13 miles north of Beluga and was en route to the Beluga Airstrip.
According to the operator's president and director of safety, the helicopter was transporting a composting toilet weighing about 1,000 pounds attached to a lightweight, synthetic, 100-foot long-line. A ground crewmember heard the pilot announce over the company radio frequency, "I'm going down." No further radio communications were received. About 30 minutes after the accident, the Alaska State Troopers received a 911 distress call from the injured pilot via cell phone. The operator reviewed Sky Connect satellite tracking data and relayed the last known position to searchers. The wreckage was located by another helicopter working in the area.
In a written statement, the pilot reported that he had been flying a company Eurocopter AS350 B2 earlier, but on the accident day he flew the AS350 B3 for the first time on that project. He elected to use the same long-line from the B2, which had a weighted hook painted orange/red for visibility against snow, but the lightweight synthetic 100-foot long-line did not have a rotating swivel.
After ground crew attached the long-line and load, the pilot hovered and ascended vertically to check for knots or kinks. He lifted the load and climbed to 1,000–1,500 feet above sea level. At 70 knots, the load began flying erratically, spinning and swinging. He slowed to 60–65 knots, where the load flew with a gentle slow spin and minimal lateral motion. About 2 miles from the airstrip, at 1,000 feet, he felt a tug and noticed the load behaving differently, suspecting a broken strap. Unable to see the load, he felt the helicopter yaw, then spin, and jettisoned the load using the mechanical release. The helicopter continued spinning uncontrollably; he reduced throttle and descended into trees, coming to rest on its left side.
Pilot Information
The pilot, aged 29, held a commercial pilot certificate with a helicopter rating and a second-class medical certificate issued March 8, 2012. He had about 3,037 total flight hours, including 48 hours in the accident make and model, with 32 hours in the preceding 90 days.
Aircraft Information
The helicopter was a Eurocopter AS350 B3, manufactured in 1982, equipped with an Arriel 2B turboshaft engine. It had about 5,558 hours at the time of the accident and was maintained under a manufacturer's inspection program; a 100-hour inspection was completed on August 13, 2012. Examination of logbooks revealed no pre-accident mechanical issues. The helicopter was equipped with a Sky Connect satellite tracking system; data showed no unusual tracks until the loss of control.
Meteorological Information
The closest weather reporting facility was Anchorage International Airport, 32 miles east. At 0953, a METAR reported wind from 340 degrees at 3 knots, visibility greater than 10 statute miles, few clouds at 7,000 feet, temperature 7°F, dew point 3°F, altimeter 29.15 inches Hg. VFR conditions existed.
Wreckage and Impact Information
The helicopter was not examined at the remote crash site. Photographs showed it descended through heavily treed terrain and came to rest on its left side, with substantial damage to the fuselage, tail boom, and rotor system. The operator located the sling and load near the accident site. The load was a metal self-composting toilet weighing about 1,000 pounds, equipped with a 4-point cable harness attached to a D-ring and a non-swiveling hook. The synthetic long-line was about 100 feet long with an electrically actuated hook at one end and a large D-ring at the other, attached to the non-swiveling belly hook. Photographs showed the harness cables and lifting line twisted and knotted at the load end; the line separated with frayed ends about midway. The section above the separation, about 40 feet long, was wrapped tightly around the tail rotor gearbox output shaft, and the tail rotor gearbox had twisted free from its mounts and departed the helicopter in-flight.
Additional Information
The long-line was a synthetic woven braided line about 100 feet long with loops on each end, without attachments or hardware. Suitable attachments could be added depending on the mission. The operator had an FAA-approved training program for Part 133 certification. The pilot had about 290 hours of long-line experience, most with Prism Helicopters, in several helicopter makes and models. He stated that during training he was never instructed on using a drag/drogue chute to stop load spinning, and the operator did not have chutes available. 14 CFR Part 133 and FAA Advisory Circular 133-1A provide guidance for external-load operations but do not address rigging; the military field manual FM 4-20.198 describes rigging procedures for recurring loads.