WPR11FA138

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.

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,