Hanapepe, HI, USA
N29EP
AirBorne WindSport Edge XT-912-L
During the student pilot’s initial instructional flight, a witness observed the weight-shift-control (WSC) aircraft flying low over a cultivated field that sloped toward the ocean. When the aircraft reached the end of the field, the witness lost sight of the aircraft as it descended below the edge of a 100-foot cliff that dropped into the ocean. Other witnesses said that the aircraft leveled off about 50 feet above the water and that they then heard the engine sputter and “fire back up.” Two of the witnesses thought that the aircraft was going to land on the water, but then it pitched up and climbed straight into the air for 2 to 3 seconds before the engine became silent, and the aircraft fell back into the ocean and sank. The wreckage was recovered 6 days later. Postaccident examination revealed damage to the airframe consistent with the aircraft impacting the ocean on its left side. No abnormalities were found with the airframe that would have precluded normal operation. The engine’s flywheel cover was removed and rotational scoring marks were found on the inner surface, indicating that the engine was rotating at the time of impact. A serviceable starter was installed on the engine, and the engine rotated and started, but would not run continuously. The engine was disassembled, and evidence of corrosion, due to salt water immersion, was found on all of its components. No evidence was found of any preimpact mechanical malfunctions or failures that would have prevented the engine from operating normally. It is likely that the postaccident corrosion was the reason that the engine would not run continuously. The engine’s choke lever, which was located on the left side of the tandem seat frame and accessible to both occupants, was found in the on position. According to an experienced WSC aircraft operator, activation of the choke in flight produces a coughing sound and results in a momentary reduction of engine power. The physical evidence and witness observations suggest that the choke was inadvertently activated, and, after the ensuing momentary interruption in engine power, the flight instructor lost control of the aircraft while maneuvering at low altitude. It could not be determined whether the choke was activated by the student or the flight instructor.
HISTORY OF FLIGHT On February 15, 2011, about 1140 Hawaiian standard time, an AirBorne WindSport Edge XT-912-L weight-shift-control (WSC) light sport aircraft N29EP, was substantially damaged when it impacted the water near Hanapepe, Hawaii. The sport pilot instructor and his student sustained fatal injuries. The WSC aircraft sank in about 50 feet of water and was recovered 7 days after the accident. Big Sky Kaua’i was operating the aircraft under 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the local instructional flight. The WSC aircraft departed from Port Allen Airport, Hanapepe, Hawaii, about 1045. Moments before the accident, a coffee plantation worker observed the aircraft flying downslope towards the ocean. He said it was about 3 to 4 telephone poles in height above him. The coffee field that the WSC aircraft was flying over sloped from about 200 feet to 100 feet in elevation, at which point it ended at a cliff that dropped straight to the ocean. The worker stated that he lost sight of the aircraft as it dipped below the cliff line flying nearly due south towards the ocean. The witness stated that he had seen the aircraft many times before. He said that the aircraft appeared a little bit lower than during previous flybys, but its engine sounded fine. He never regained sight of the aircraft. A witness on a fishing boat stated that the aircraft leveled off at about 50 feet above the water and turned approximately west towards the Port Allen Airport. Another witness, who was in a kayak on the ocean, said the aircraft was flying away from the cliffs in the general direction of Port Allen. He thought it was about 50 feet above the water when he heard the engine sputter, and then “fire back up.” At first, he thought the aircraft was going to land on the water, but when the engine “fired back up,” the aircraft turned straight up into the air. The witness estimated that it went 100 feet up, almost to the top of the cliff. As it nearly reached the height of the cliff, the engine went silent. He said that next the aircraft nosed straight down and impacted the ocean. A third witness first saw the WSC aircraft when it was near the 100-foot-high cliff, and was about 50 feet above the water. She said the aircraft was facing out towards the ocean, and she thought it was going to land on the water. Then she heard the engine go “putt, putt, putt.” Next it pulled up until its nose was facing straight up into the air. The aircraft continued up and appeared to do a vertical climb for a second or two. At that point, the engine went “dead silent,” and it fell straight down into the ocean. Several of the kayak witnesses said that when they arrived at the impact location all they found was an oil slick on the surface of the water. PERSONNEL INFORMATION The 55-year-old pilot did not have a Federal Aviation Administration (FAA) medical certificate. His status as a sport pilot and flight instructor for sport pilot in WSC aircraft required only a current driver’s license. He also held a repairman certificate for light sport airplanes and WSC aircraft. The pilot’s flight logbook was never recovered, and no documentation of his flight experience was found. The 49-year-old student did not have an FAA medical certificate, nor was one required for an introductory flight in a WSC aircraft. A friend of the student reported that the student had never been for a flight in a WSC aircraft, and to the best of her knowledge the student had never been for a flight in a small general aviation aircraft. AIRCRAFT INFORMATION The single-engine (pusher), propeller-driven, two seat tandem WSC aircraft was manufactured by AirBorne Windsports Pty. Ltd., Redhead, New South Wales, Australia, on May 24, 2006. Its maximum takeoff gross weight was 992 pounds; it had an empty weight of 494 pounds. It was powered by a Rotax 912 UL four-stroke engine, which had a maximum output of 80 horsepower. The aircraft had a pilot-passenger “pod” suspended by a triangular frame, hinged below the wing, which permitted weight shift control of pitch and roll axes. It was equipped with dual flight controls and a ballistic recovery parachute. Passengers in the aircraft were provided with a helmet/headset combination with noise canceling capabilities, which provided for communication between the two occupants. Each occupant was provided with an automatic inflatable personal flotation device. The engine’s fuel supply was carried in a molded plastic tank, which was behind and under the aft occupant’s seat. It held about 18.5 gallons; the engine used between 3 to 3.5 gallons per hour. A choke lever was on the left side of the pilot's seat frame, which made it accessible to both occupants. Forward movement of the choke lever was to the on position or rich; it was used for starting the engine only. The four cylinder engine was equipped with two carburetors; each of the carburetors had a built in “starting” carburetor. These two small carburetors were activated with a single choke lever, which provided a limited enriched fuel air mixture for starting the engine. During normal engine operation, enriching the fuel-air ratio with the choke will produce a coughing sound and would result in a momentary reduction of engine power output. This phenomenon would be more pronounced at lower power settings. The owner purchased the aircraft on February 25, 2010; no aircraft records were located for the period before this date. The aircraft was assembled in Hawaii on February 27, 2010, and the maintenance logbooks were started at zero hours. The last 100-hour condition inspection was completed by the pilot, on January 25, 2011. At that time, the maintenance records indicated that the aircraft had accumulated 698 flight hours. The manufacturer of the aircraft had published a Pilot’s Operating Handbook (POH), which included Operational Limits for the aircraft. This section included the following statement concerning maneuvering limits: “All aerobatic maneuvers including spinning are prohibited. Aerobatic maneuvers including whipstalls, stalled spiral descents, and negative G maneuvers are not permitted. It must be emphasized that a whipstall, spiral descent, or negative G maneuvers can never be conducted safely. These maneuvers put the aircraft outside the pilot’s control, and put both the aircraft and its occupants in extreme danger. Do not pitch nose up or nose down more than 45 degrees from the horizontal. The front support tube of the trike [aircraft] and the pilot’s chest limits the fore and aft movement of the control bar respectively. BANK ANGLE Do not exceed 60 degrees of bank angle. In roll there is no stop for the control movement. For the purpose of pre-flight freedom, check by lowering each wing to within 10 cm of the ground (on ground level).” Additionally, the POH stated that flight load factors are limited to 4.0 “G” positive, load factors from 1.0 “G” positive to 0.0 “G” should be avoided, and any negative loads less than 0.0 “G” prohibited. METEOROLOGICAL INFORMATION At 1153, the reported weather conditions at Lihue Airport, Lihue, Hawaii, located 13 nautical miles northeast of the accident site, were: wind from 110 degrees at 6 knots; visibility 9 statute miles; clear of clouds; temperature 77 degrees Fahrenheit; dew point 70 degrees Fahrenheit; altimeter setting 30.10 inches of Mercury. Two witnesses in a kayak stated that there “was not much wind” at the time of the accident. WRECKAGE AND IMPACT INFORMATION The WSC aircraft was found in approximately 45 feet of water and about 125 feet from shore. The two occupants were removed by local search and rescue personnel the day after the accident. The divers noted that the ballistic recovery system had not been activated. Six days later, the aircraft was recovered from the bottom of the ocean. Due to lack of lifting equipment on the small salvage boat, the wreckage was brought to the surface with marine lift bags and towed to Port Allen, approximately 2.8 miles away. During the recovery, it was noted that the ballistic recovery system had fired during the time the aircraft had been on the ocean’s bottom. On March 8 and 9, 2011, a team was assembled to examine the wreckage in a hangar at Lihue Airport. The team was comprised of a National Transportation Safety Board investigator, two Federal Aviation Administration inspectors, manufacturer representatives from the engine and airframe companies, and a local WSC subject matter expert. Postaccident examination of the aircraft found that the wing frame was damaged at the left forward wing support tube, left wing tip, and left cross tube. The left side of the oil sump was deformed; the left main landing gear strut was bent inward. This physical evidence is consistent with the aircraft impacting the water on its left side. The engine exhibited internal continuity, and thumb compression was noted on all four cylinders. The engine’s choke was found frozen in the on position. The plastic flywheel cover was removed and rotational scoring marks were found on the inside, consistent with engine rotation at the time of impact. Two of the three propeller blades had separated at the hub. A serviceable starter was installed, and the engine fired and rotated. The engine did not run continuously. The engine was completely torn down. Considerable evidence of corrosion to all engine components, as a result of salt water immersion, was noted during the tear down. No abnormalities were found with the airframe or engine which would have precluded normal operation prior to ocean impact and salt water contamination. The Dacron fabric in the main sail of the wing when new has a pull test limit of 3,300 grams and the stitching has a limit of 4,100 grams. The maintenance manual for the WSC aircraft states that the pull test lower limit for the wing is 1,360 grams. On the accident aircraft, the top side of the wing fabric failed a pull test at between 600 and 675 grams. The bottom side of the wing fabric tested within limits. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy of the pilot was conducted by the Pacific Pathologists, LLC. for the coroner of Kaua’i, Hawaii, on February 18, 2011. The FAA’s Civil Aeromedical Institute (CAMI), Oklahoma City, Oklahoma, performed toxicology tests on the pilot. According to CAMI’s report, the pilot’s blood was tested for carbon monoxide, cyanide, and drugs with negative results. Ethanol was detected in the pilot’s blood, but it was determined to be from sources other than ingestion. ADDITIONAL INFORMATION The WSC subject matter expert provided the following information. On a recent takeoff in an identical make and model WSC aircraft with a student in the back seat, she suddenly experienced a rough running engine. She landed straight ahead and examined the engine, but no abnormalities were found. When she applied the choke at various throttle settings, she was able to reproduce a similar sounding rough running engine. Because of the location of the choke on the seat rail, she concluded that her backseat student inadvertently moved the choke to the on/rich position. Records reviewed during the investigation included a liability release form that was completed and signed by the student on the date of the accident. The form was titled, “Light Sport Aircraft (WSCL) Flying Release of Liability, Waiver of Legal Rights and Assumption of Risk.” The form stated, in part: “In consideration for the use, renting, purchasing or leasing of Light Sport Aircraft (WSCL), and/or other related equipment or services from Port Allen Airport, Hanapepe, HI, and/or the use of the facilities, ground school, instruction, premises and equipment of BIG SKY KAUAI, LLC., in connection with my participation in Light Sport Aircraft (WSCL) flying, ground instruction, flight instruction, ultra light soaring, and related activities (hereinafter collectively called “micro light flying/gliding”) I hereby understand and agree to this release of liability, waiver of legal rights and assumption of risk as follows:” According to Federal Aviation Administration regulations, Title 14: Aeronautics and Space, Part 91.327, Aircraft having a special airworthiness certificate in the light-sport category: Operating limitations. (a)No person may operate an aircraft that has a special airworthiness certificate in the light-sport category for compensation or hire except--- (1)To tow a glider or an unpowered ultralight vehicle in accordance with 91.309 of this chapter; or (2)To conduct flight training. (e) Each person operating an aircraft issued a special airworthiness certificate in the light-sport category must advise each person carried of the special nature of the aircraft and that the aircraft does not meet the airworthiness requirements for an aircraft issued a standard airworthiness certificate.
The flight instructor did not maintain aircraft control while maneuvering at low altitude. Contributing to the accident was the inadvertent application of the choke, which resulted in a momentary interruption of engine power.
Source: NTSB Aviation Accident Database
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