WPR10FA440

In-flight impact of a passenger's metal clipboard with the helicopter’s tail rotor, which resulted in destruction of the tail rotor and subsequent loss of control of the helicopter. The original location of the clipboard and how it became free could not be determined.

Two state biologists planned to conduct an aerial wildlife survey in a commercially-owned helicopter equipped with a three-abreast bench seat and a fully enclosed cabin. After briefing with the biologists, the pilot stowed most of the biologists' equipment and personal effects on the helicopter's external racks, and all three boarded the helicopter, with the biologists in each of the outboard seats. The plan was to conduct a fuel stop at one of the operator's fuel trucks located about 80 miles east of the departure airport, and then conduct the survey in the region near the fuel truck. The helicopter departed, and 6 minutes later, the state communications center received the first automated flight-following transmission. About 33 minutes later, the pilot broadcast that the helicopter was “landing at Kamiah,” which was about 35 miles short of the planned destination. An exact correlation between the time of the transmission and the accident time could not be determined, but the transmission was very likely within 4 minutes of the accident, and possibly much closer. No further transmissions were received from the helicopter. Several witnesses observed the helicopter transiting west to east, then heard unusual noises emanating from the helicopter and observed objects separating or falling from it. Several witnesses reported that it was rotating as it descended; one witness stated that the nose was “dipping” up and down, and other witnesses reported that the trajectory steepened as the helicopter descended. The main wreckage was found in the driveway of a residence, and a 1,500-foot debris field was oriented back along the helicopter's flight path; some of the items at the beginning of the debris field included tail rotor blade and tail rotor gearbox segments, and fragments of a metal clipboard that belonged to one of the biologists. Witness marks on the tail rotor and clipboard clearly indicated that the clipboard struck and separated the tail rotor, which resulted in the loss of control of the helicopter. Helicopter geometry and aerodynamics suggested that the clipboard originated from the left side of the helicopter. The investigation was unable to determine why the helicopter diverted to Kamiah. One of the biologists was reported to be susceptible to airsickness. Anti-nausea wristbands were found in the external luggage, but they could not be definitively associated with any particular person on the helicopter. The landing diversion could have been to allow a biologist to access the wristbands, to prevent the biologist from getting sick in the helicopter, or to allow the biologist to discontinue the flight altogether. Other speculative reasons for the diversion include a problem with the helicopter, the need for one of the biologists to retrieve something other than the medication from the externally-stowed luggage, or the need to retrieve the clipboard that was inadvertently left unsecured on one of the external racks. Because the fuel stop was planned to occur prior to beginning the survey, that stop would have provided the opportunity to retrieve any survey-related articles from the stowed luggage; thus it is unlikely that survey equipment was needed at that time. Aside from the clipboard-induced tail rotor system damage, examination of the helicopter and engine did not reveal evidence of any preimpact condition or failure that would have precluded normal operation or continued flight. There was no evidence that anyone actually got sick during the flight. Therefore, the landing diversion was likely either to provide an opportunity to somehow address the airsickness issue, or to retrieve the misplaced clipboard. It could not be determined whether the clipboard originated from inside or outside the cabin. If the clipboard were inside the cabin at the beginning of the flight, the only exit path would be via an open door. If a door were opened either intentionally or unintentionally, the clipboard could have exited either because it was near the door or because it was already resting on the bubble window at the time. Although one witness stated that the right cabin door was open in flight, the damage patterns indicated that both cabin doors were closed at impact. However, this does not mean that the door was not opened during the flight, and then closed during the descent. Although a witness stated that all external cargo items were secure before takeoff, it is possible that the clipboard was inadvertently left on an external baggage rack, went unnoticed until the helicopter was in flight, and was the reason for the diversion. Flight path data indicated that the helicopter was in a continuous climb until about 5 minutes prior to the accident. Since the cargo racks had mesh floors, the clipboard might have been held in place by the external airloads during the climbing portion of the flight and was only dislodged by altered airflow during the descent for the diversionary landing. Although two witnesses saw geese in the vicinity of the helicopter, there was no evidence of a bird strike. Several noteworthy safety-related discrepancies were revealed during the investigation, even though they did not directly contribute to the accident or its severity. The genealogy of the helicopter could not be clearly established and remained suspect. Although the helicopter bore what appeared to be the manufacturer's original data plate, the accident helicopter configuration differed significantly from the as-delivered configuration, and there were no appropriate means of converting the as-delivered configuration to the as-found configuration. In addition, the helicopter was not in conformance with at least two contractual requirements regarding flight safety equipment. Finally, the state flight-following service, which was responsible for monitoring the progress of the flight, had to be prompted by the operator to determine the status of the flight after the helicopter disappeared from the operator's flight-following display.

HISTORY OF FLIGHT On August 31, 2010, about 0929 Pacific daylight time (PDT), a Hiller UH-12E helicopter, N67264, was substantially damaged when it impacted utility lines, a travel trailer, and the ground in Kamiah, Idaho, about 35 minutes after departure. The commercial pilot and the two passengers, both of whom were biologists with the Idaho Department of Fish and Game (IDFG), were fatally injured. The helicopter was owned by Leading Edge Aviation (LEA), and was under the operational control of IDFG as a wildlife survey flight. The flight was conducted under the provisions of Title 14 Code of Federal Regulations (CFR) Part 91, and in accordance with the IDFG Clearwater Region "Regional Summary of Procedures for Monitoring Low Level Aerial Survey Operations," dated December 31, 2009. Visual meteorological conditions prevailed. A notification for automated flight following (AFF) was filed and activated with the Idaho State Communications Center, referred to as "StateComm." The biologists arrived at the LEA helicopter base, Skid Row Seaplane Base (WT33) Clarkston, Washington, about 0800. Flight preparations and briefings were conducted, and most of the biologists' gear was secured in cases on external racks on the helicopter. The plan was for the helicopter to fly about 70 miles to the east to rendezvous with an LEA fuel truck, refuel, and then conduct the survey. The pilot seated himself in the center seat, the female biologist was in the right seat, and the male biologist was in the left seat. The helicopter departed WT33 about 0850, and the first AFF return from the helicopter was received about 6 minutes after that. About 33 minutes later, StateComm received a radio call from the helicopter, announcing that it intended to land in Kamiah. No explanatory or additional transmissions were received from the helicopter. Kamiah was a small town situated about 30 miles short (west) of the planned fuel stop. Several eyewitnesses in Kamiah reported that they first observed the helicopter transiting west to east. They then heard unusual noises emanating from the helicopter, and observed objects separating or falling from the helicopter. Several noted that the helicopter was gyrating or rotating about its longitudinal or vertical axes, and that the trajectory steepened as the helicopter descended. The main wreckage, which consisted of the cabin, tail boom and main rotor system, impacted in a driveway of a residence. Two of the occupants received immediate fatal injuries, while the third survived for several minutes after the impact. A debris path that was oriented back (west) along the helicopter's flight path, and that measured approximately 1,500 feet in length, was comprised of various items from the helicopter. Some of the earliest items in the debris path included the tail rotor blade and tail rotor gearbox segments, and fragments of a metal clipboard that belonged to one of the biologists. PERSONNEL INFORMATION The pilot was an employee of LEA. He held a commercial pilot certificate with a helicopter rating. According to information provided by LEA, he had approximately 9,000 total hours of flight experience, all of which was in helicopters, and which included approximately 300 hours in the accident helicopter make and model. His most recent flight review was completed in October 2009, and his most recent Federal Aviation Administration (FAA) second-class medical certificate was issued in October 2009. The Lewis County (Idaho) Coroner's Office autopsy report indicated that the cause of death was "blunt force trauma." The FAA Civil Aeromedical Institute conducted forensic toxicology examinations on specimens from the pilot, and reported that no carbon monoxide, cyanide, ethanol, or any screened drugs were detected. According to IDFG information, the pilot was properly "carded" (trained and approved by the Aviation Management Directive (AMD) of the National Business Center (NBC) of the United States Department of the Interior, in accordance with IDFG contractual requirements) and was current with regard to all other IDFG qualifications. The flight was the first scheduled flight of the day, and the pilot was within the duty day and other crew requirements or limitations established by the contract. The pilot and both biologists were wearing the required aviation life support equipment at the time of the accident. Both biologists were current with respect to their IDFG-required aviation safety training, and both had an extensive history of low altitude flights. The male biologist was a private pilot with approximately 10 years of flight experience, and owned a single-engine airplane. He also had about 10 years of experience with the same type of survey that was planned for the accident flight; most of those flights were conducted in helicopters. Also according to IDFG information, the female biologist had conducted extensive low-altitude fixed-wing survey flying between the years 2000 and 2004. It was reported by some IDFG personnel that she may have been susceptible to airsickness, but no definitive evidence or documentation of this was provided for the investigation. Autopsies were not conducted on either biologist. AIRCRAFT INFORMATION Overview According to FAA records, the helicopter was manufactured in 1965, and was converted to turbine power in 1981. Information provided by LEA indicated that at the time of the accident, the helicopter had accumulated a total time (TT) in service of 7,388 hours. Review of maintenance records indicated that the most recent annual inspection was completed in April 2010. At that time, the airframe had a TT of 7,168 hours, while the engine had a TT of 7,432 hours. The most recent 100-hour inspection was completed in July 2010, and the helicopter had accumulated about 80 hours in service since that inspection. General Configuration Information The basic configuration consisted of 3-place-abreast seating in a metal-frame and plastic transparency "bubble cabin," a two-bladed metal main rotor, and a two-bladed metal tail rotor (painted red). Specific configuration details included: - A metal "seat deck"' which was the primary structural element of the cabin - Metal-framed left and right side cabin doors - A vertical firewall that also served as the aft cabin wall - A central pilot's seat with an instrument/control pedestal, and flight controls - Left and right external racks (approximately 6 feet long, 2 feet wide, and 4 inches deep, with metal mesh bottoms) - Main rotor rotation counter-clockwise when viewed from above - A metal, semi-monocoque tail boom - Multi-segment tail rotor drive system mounted atop the tail boom - Tail rotor gearbox at the aft end of the tail boom - Tail rotor rotation counter-clockwise when viewed from helicopter left side - Single metal horizontal stabilizer on the right-side end of the tail boom METEOROLOGICAL INFORMATION The 1030 automated weather observation at Kamiah Municipal Airport (S73), Kamiah, included calm winds; clear skies; temperature 16 degrees C; dew point 10 degrees C; and a barometric pressure of 29.99 inches of mercury. Visibility values were not recorded, and no precipitation was recorded in the 12 hours preceding the accident. AIDS TO NAVIGATION A handheld Garmin GPSMap 396 global positioning system (GPS) unit was found in the main wreckage, and mounting, antenna, and power provisions for the unit were attached to the helicopter. The unit was recovered and shipped to the NTSB Recorder Laboratory in Washington DC. Data downloaded from the GPS unit indicated that a pre-stored route entitled "Skid Row - S73" was active for the flight. COMMUNICATIONS "StateComm" According to its website, StateComm was an emergency communications center that operates continuously, to provide emergency dispatch and communications for State and public health- and safety-related situations or emergencies