Kahoolawe, HI, USA
N3280U
Bell UH-1H
The commercial helicopter had delivered an external load, and was returning to another site with a 41-foot, unweighted external load cable still attached under the helicopter. A witness saw the helicopter overhead, and watched as the cable slapped the fuselage, and became entangled with the tail rotor. The tail rotor subsequently separated from the tail boom, and the helicopter rolled nearly inverted and crashed. Examination of the wreckage revealed cable witness marks on the tail boom and tail rotor blades. The commercial pilot had extensive flying experience conducting external load operations. The operator indicated it was not their standard procedure to have an unweighted cable attached to the helicopter for transition flights.
HISTORY OF FLIGHT On May 22, 2003, at 1150 Hawaiian standard time, a Bell UH-1H single-engine helicopter, N3280U, was destroyed following an in-flight breakup after its 41-foot external load cable became entangled with its tail rotor over the island of Kahoolawe, Hawaii. The helicopter was registered to Pacific Helicopter Services LLC, of Kahului, Hawaii, and operated by Pacific Helicopter Tours, Inc., of Kahului. The commercial helicopter pilot, who was the sole occupant, was fatally injured. The flight was operated under the provisions of CFR Part 133 Rotorcraft - External Loads. The flight departed a landing zone (LZ) on Kahoolawe approximately 5 minutes prior to the accident, and was destined for Puunene, on the island of Maui, Hawaii. Visual meteorological conditions prevailed at the time of the accident and a flight plan was not filed. According to the operator, the pilot had conducted three external load transports earlier that day between Puunene and Kahoolawe, with the last one being a 3,000-pound fuel pod via its 41-foot external load line. The pilot dropped off the fuel pod at LZ Squid and departed with the 41-foot line still attached. One witness, located on the island of Kahoolawe, indicated he heard the helicopter fly overhead and looked up. He observed the helicopter with an "unweighted cable swinging free under the aircraft." The witness saw the cable "slap the undercarriage one time before the cable impacted the tail rotor." He then observed the tail rotor coming apart. The witnessed looked away from the helicopter shortly (due to unstable footing) and when he looked back, the helicopter had "rotated and spun nearly upside down," and he watched it descend until impact. He added he could tell the cable was unweighted "due to the way it moved freely under the aircraft...because of the aircraft speed and the cable being unweighted, it [the cable] was able to slap the underside of the aircraft." Additional witnesses heard three loud bangs or pops described as a gunshot, explosion, or metal hitting metal. As they looked up to see the helicopter they noticed the tail rotor coming apart. One witness heard another pop and then noticed the main rotor separate from the helicopter. Another witness indicated she observed the main rotor blade rotation slow after the tail rotor debris fell from the helicopter, then the main rotor system separated. A few witnesses observed the helicopter rolling to the right. The helicopter impacted the ground inverted. By the time the witnesses reached the accident site the helicopter's cockpit/cabin section was engulfed in flames. The witnesses, who first responded to the accident site, indicated the helicopter was severely damaged and they did not receive any response from their calls to the pilot. PERSONNEL INFORMATION The pilot held a commercial pilot certificate with airplane single-engine land, airplane multi-engine land, instrument airplane, and helicopter ratings. He also held a helicopter flight instructor certificate. According to the operator, the pilot accumulated a total of 12,766 flight hours, of which 11,758 hours were accumulated in helicopters, and 1,565 hours were logged in the accident airplane make and model. Approximately ¼ of the pilot's total flight experience was accumulated while conducting long-line, external lift operations. His last FAR 135 Airmen Competency/Proficiency Check was conducted on March 21, 2003, in a Bell 206B helicopter. The pilot obtained a second-class medical certificate on May 12, 2003, with a limitation to wear "corrective lenses for near vision." A review of the operator's daily flight logs revealed the pilot worked a 14-hour duty day (3.2 hours of which were logged flying) on the 19th, an 11.50-hour day (6.6 hours of flight) on the 20th, and a 14-hour day (2.7 hours of flight) on the 21st. On the morning of the accident, the pilot logged in for work at 0530. AIRCRAFT INFORMATION The helicopter (serial number 66-16904) was a military surplus aircraft. It was established on a military phase inspection program and had undergone a phase 2 inspection on February 6, 2003, approximately 144 hours prior to the accident. The airframe accumulated a total time of 11,368.4 hours on the morning of the accident. The helicopter incorporated two external load release systems; one being an electrically operated system, which is activated by a switch located on the cyclic, and the other being a manual release system, which can be activated by stepping on a release pedal located between the anti-torque pedals. In either case, not only is the external load released, but the cable is also freed. The 41-foot line was a steel cable with a load hook positioned at the load end. The cable was not weighted for the return flight to Puunene. The distance between the cable attach point on the belly of the helicopter and the center of the tail rotor system was approximately 28.8 feet. METEOROLOGICAL INFORMATION At 1154, the weather observation facility located at the Kahului Airport (27 statute miles north-northeast of the accident site) reported the wind from 030 degrees at 18 knots, 9 statute miles visibility in light rain, a few clouds of 2,200 feet, scattered clouds at 2,900 feet, and broken clouds at 3,800 feet, a temperature of 26 degrees Celsius, and a dew point of 21 degrees Celsius, and an altimeter setting of 30.05 inches of mercury. WRECKAGE AND IMPACT INFORMATION Two Federal Aviation Administration (FAA) inspectors, who responded to the accident site, indicated the tail rotor hub separated from the helicopter and came to rest in some scrub brush. The tail rotor blades remained attached to the hub; however, the outboard section of one of the blades had separated. At the blade separation area, cable witness marks were noted. In addition, cable witness marks were visible on the bottom side of the tail boom. The main rotor blades remained intact and attached to their hub. The main rotor was located at 20 degrees 32 minutes north latitude and 156 degrees 38 minutes west longitude. The main wreckage, which included everything except the main rotor blades, the tail rotor blades, and a section of separated sheet metal, came to rest at 20 degrees 34 minutes north latitude and 156 degrees 38 minutes west longitude. The cable came to rest adjacent to the main wreckage, but was not attached to the helicopter. The wreckage was recovered to a hangar at the Kahului Airport on the island of Maui. The wreckage was examined by the FAA and NTSB again on Wednesday, May 28, 2003. The main rotor mast separated at the blade flapping stops, and displayed indentations consistent with the flapping stop locations. The mast fracture surfaces displayed 45-degree sheer lips. The engine turbine case displayed punctures from the inside out, and the turbine blades were fractured and displayed heat damage. The engine's compressor section was completely destroyed with its entire rotor and stator blades found separated and/or burned. PATHOLOGICAL INFORMATION An autopsy on the pilot was performed by the Maui County Medical Examiner's Office. According to the autopsy report, the pilot died as a result of multiple traumatic injuries. Toxicological tests for volatiles and drugs were conducted on the pilot. According to the toxicological report, 11 mg/dL of ethanol and 12 mg/dL of acetaldehyde were detected in the pilot's heart; however, the ethanol was cited as being formed from "postmortem ethanol formation and not from the ingestion of ethanol." ADDITIONAL INFORMATION According to the operator, it is not normal procedure to fly between Kahoolawe and Maui with the cable attached without a load. Review of the operator's flight and operations manuals revealed there were no policies established for flights with the cable attached, without a load. No airspeed limitations or cable length restrictions were established. The wreckage was released to the owner's representative on May 29, 2003.
The pilot's failure to remove the external load cable before the repositioning flight, which resulted in the cable striking the tail rotor in cruise flight.
Source: NTSB Aviation Accident Database
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