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On September 12, 1999, at 1500 central daylight time, a Spagnoletti Air Command 582, homebuilt gyroplane, N813AC, was destroyed when it impacted terrain during takeoff/initial climb at the Montgomery County Airport, near Conroe, Texas. The aircraft was registered to and operated by a private individual under 14 Code of Federal Regulations Part 91. The private pilot, sole occupant, received fatal injuries. Visual meteorological conditions prevailed for the personal flight, and a flight plan was not filed for the flight. The local flight originated after the builder/owner's flight at 1430.
Local authorities and witnesses reported to the NTSB investigator-in-charge (IIC) that earlier that day, the builder/owner had performed a preflight during which he went over the entire gyroplane and found no discrepancies. The builder/owner then flew the gyroplane at approximately 1430, and following his flight, no aircraft discrepancies were reported. During a telephone interview with the NTSB IIC, he stated that the "gyroplane was 100 percent perfect for flight."
The accident pilot taxied the gyroplane to runway 14 for departure. Following the takeoff, the pilot flew the gyroplane approximately 10 to 15 feet above the runway, landed on runway 14, exited at Taxiway Charlie, and taxied to the ramp. At the ramp, the pilot remained in the gyroplane and talked with the builder/owner for several minutes.
A subsequent takeoff was performed on runway 19. Witnesses reported that the gyroplane began to gain altitude, "it was in stair step increments not a smooth transition." During the climb to approximately 250 feet agl, the gyroplane was observed to "list to the left," and the engine seemed to "power down, like it was under a load." Subsequently, power was applied, and the gyroplane was at "approximately a 60 degree angle" in a "sharp right bank" when the rear main rotor blade appeared to stop moving and the front main rotor blade appeared to fold back on itself. Witnesses observed the gyroplane, under full power, nose dive onto the right side of Taxiway Delta and continue into the grassy area near the taxiway before coming to rest. One witness stated that the gyroplane "pitched down, then pitched up, then seemed to pitch down again when it suddenly quit flying and went straight down." The builder/owner stated that the pilot "unloaded the blades, the blades flapped, and with the engine at full power, the gyroplane entered a somersault."
According to FAA records and the pilot's logbook, on April 11, 1998, the pilot obtained a private pilot certificate with the single-engine land rating. In August and September, 1997, the pilot logged 2.3 hours in an Air Command Tandem Gyroplane. On July 24 and 25, 1998, the pilot received 2.9 hours of dual instruction in a Twin Starr Gyroplane. On August 8, 1998, the pilot logged 0.7 hour flight in the Air Command Gyroplane. Prior to the accident flight, the pilot had accumulated 140 hours of flight time in fixed wing airplanes.
During a telephone interview, the aircraft builder/owner stated that the pilot had approximately a total of 10 hours in the gyroplane; however, he had not flown a gyroplane in a year.
The 1997 Air Command 582, single place, open cockpit, single rudder, gyroplane was powered by a 130-horsepower Yamaha 1,100 cubic centimeter engine with a 3-bladed pusher-type composite propeller. The gyroplane was equipped with a teetering rotor system. The gyroplane was also equipped with an altimeter, an engine tachometer, a rotor tachometer, and an airspeed indicator. The gyroplane was equipped with a pre-rotator motor and gear to power the main rotor prior to takeoff.
An aircraft registration certificate for N813AC, which listed a private individual as the builder/owner of the gyroplane, was issued by the FAA on August 7, 1997. On September 8, 1998, the FAA issued the gyroplane a permanent special experimental amateur-built airworthiness certificate.
According to the airframe logbook, the most recent condition inspection occurred on April 1, 1999. At the time of the inspection, the gyroplane had accumulated 61.0 hours. The builder/owner reported that the gyroplane had accumulated 100 hours total flight time as of the day of the accident.
At 1453, the weather observation facility at the Montgomery County Airport reported the following weather conditions: wind calm, few clouds at 6,000 feet, visibility 10 statue miles, temperature 91 degrees Fahrenheit, dewpoint 64 degrees Fahrenheit, and altimeter 29.94 inches of Mercury. The unicom operator and the airport manager reported that the winds were from the southeast at 5 knots at the time of the accident.
WRECKAGE AND IMPACT INFORMATION
The main wreckage distribution path was 81 feet in length and oriented on a magnetic heading of 220 degrees. The first piece of wreckage, located at the beginning of the main distribution path on Taxiway Delta, was identified as the engine air filter. Green paint transfer and imprints of the main rotor system retaining bolts were found along the taxiway portion of the distribution path. The rudder, and elevator, both carburetors, and nose wheel assembly were found along the southwest edge of the taxiway. The main wreckage was located in a grassy area 46 feet from the initial impact point and 24 feet southwest of the taxiway. The main wreckage consisted of the cockpit, the engine, the steel keel frame of the gyroplane, and the main rotor system. The aircraft radio was found 35 feet beyond the main wreckage.
A four foot portion of one main rotor blade was found approximately 1,000 feet northeast of the initial impact point of the main wreckage. The main rotor blades remained attached to the rotor hub bar assembly. The outboard 7 feet 6 inches of one blade was found curled upward and over the top of the mast, pre-rotator gear, and pre-rotator motor. The other blade was curled downward and below the top of the mast, pre-rotator gear, and pre-rotor motor, and was missing a 4-foot section from the inboard trailing edge. All main rotor retaining bolts were secured through both rotor blades. No mechanical marks or dents were noted along the entire length of the leading edges of both main rotor blades. Wear was noted on the top of the pre-rotor gear and the surfaces of the gear splines. The main rotor blade, the 4-foot section of blade, the pre-rotator gear and pre-rotator motor were forwarded to the NTSB Materials Laboratory for further examination.
The Warp Drive propeller blades (3) exhibited linear chordwise separation, and each of the 3 blades separated at a different length. The propeller separated from the engine at the propeller flange, and the separation surfaces exhibited deformation with a 45 degree shear plane consistent with overload fractures. Both carburetors separated from the engine, and fuel was found in the carburetors.
The elevator bolts and the flight control tubing were separated and exhibited deformation consistent with overload fractures.
The pilot's seat belt assembly remained attached to the airframe. The seat belt was found in the latched position.
MEDICAL AND PATHOLOGICAL INFORMATION
The autopsy was conducted by the Harris County, Texas, Medical Examiner. Toxicological testing was performed at the FAA Civil Aeromedical Institute's (CAMI) Forensic Toxicology and Accident Research Center at Oklahoma City, Oklahoma. The toxicological tests were negative for drugs and alcohol.
TEST AND RESEARCH
NTSB metallurgical examinations of the separated trailing edge bond line of the main rotor blade found indications of a mixed mode (cohesive and adhesive) separation. The debonded areas were all relatively small in comparison to the total bond area and generally isolated from each other and from the exterior edge. No evidence of growth was apparent at the debonds. At several locations the trailing edge was separated and gaped open consistent with compression buckling.
The pre-rotator gear teeth were dented and damaged for about 3/4 of the gear circumference. The shape of the dents in the gear teeth matched the shape of the non-pressure faces of the pre-rotator motor gear. However, to match the gear ring dents, the motor had to be at a "severe angle to the plane of the pre-rotator gear." The rotator motor mounting block also showed damage consistent with contact by the pre-rotator gear. The damage indicated that the "motor was at a severe angle to the gear at the time of contact." Both the damage to the motor mount and to the gear teeth would "only match when the gear of the motor was retracted and not when extended." The main rotor blade teetering bolt was straight but denting and flattening was found on the edges of the blade cradle, consistent with contact from "severely tilted blades."
The aircraft was released to the builder/registered owner.