EARLY, TX, USA
N6147N
SNOBIRD 532
A STUDENT PILOT LOST CONTROL OF HIS HOMEBUILT GYROPLANE ON ITS MAIDEN FLIGHT. DUE TO THE LOW CEILINGS AND HIGH WINDS, THE PILOT ELECTED TO RESTRICT HIS MORNING TRAINING SESSION TO GROUND RUNS AND SHORT HOPS OVER THE RUNWAY. DURING THE FIFTH LOW FLIGHT, THE GYROPLANE WAS OBSERVED HIGHER OVER THE GROUND THAN ON ANY OF HIS PREVIOUS RUNS, AND AS THE AIRCRAFT APPROACHED THE END OF THE RUNWAY, FULL POWER WAS HEARD BEING APPLIED AND A STEEP CLIMB ESTABLISHED. WITNESSES REPORTED THAT AFTER TURNING DOWNWIND, WHILE STILL OPERATING AT FULL TAKEOFF POWER, A PROGRESSIVE PORPOISING LIKE OSCILLATION DEVELOPED FOLLOWED BY A LOSS OF CONTROL. THE GYROPLANE WAS OBSERVED DESCENDING RAPIDLY TUMBLING END OVER END UNTIL IT DISAPPEARED BEHIND A TREE LINE. THE TRIM SPRING USED TO PROVIDE SENSITIVITY AND STABILITY TO THE ROTOR SYSTEM WAS FOUND OUT OF ADJUSTMENT
HISTORY OF FLIGHT On April 24, 1993, at approximately 0812 central daylight time, a Snobird 532, N6147N, was destroyed upon impact with terrain following a loss of control while in the traffic pattern near Early, Texas. The student pilot, also the owner, was fatally injured. Visual meteorological conditions prevailed for the solo training flight. According to witnesses at the airport, the student pilot, also the builder of the gyroplane, transported the aircraft to the Ground Loop Airport, a privately owned airstrip near Early, Texas, for its maiden flight. Due to the low ceilings and high winds the morning of the accident, the pilot elected to restrict his maiden flight to ground runs and several short hops over the runway. The pilot was observed making four normal takeoffs and fly five to ten feet above the runway and terminating with a landing at the departure end of the strip. On the fifth takeoff, the pilot was observed higher over the ground than on his previous runs, and as the gyroplane approached the end of the runway, full power was heard being added and a steep climb established, climbing to 300 feet AGL as he continued on the runway heading for approximately three quarters of a mile when he encountered strong winds and turbulence. Witnesses further reported that after the gyroplane turned downwind, a progressive porpoising like oscillation developed and after three complete oscillations, a cracking sound was heard. The gyroplane was observed descending rapidly tumbling end over end until it disappeared behind a tree line. The engine was reported to have remained at full power during the entire accident sequence. PERSONNEL INFORMATION The pilot built the gyroplane over a two and a half year period. According to the pilot's flight instructor, a gyroplane CFI, the pilot received 14 hours of dual instruction and had been signed off to solo in August 1992. He returned to fly with him for some additional training and his 90 day solo sign off. His instructor recalled telling the student pilot to fly in calm, no wind conditions until he had at least 25 hours of solo time. AIRCRAFT INFORMATION According to the Hobbs meter installed on the gyroplane, total time on the aircraft was half an hour. The gyroplane's trim bracket was located 15 inches from the top of the mast. The trim spring was found slack. According to another gyroplane builder and pilot, the slack on the trim spring would have required the pilot to maintain considerable back pressure on the control stick in the straight and level attitude. He added that the improperly adjusted spring increased the sensitivity of the flight control and decreased the stability of the gyroplane. WRECKAGE AND IMPACT INFORMATION After ground impact, the gyroplane came to rest on its right side on a measured heading of 55 degrees. The bottom rear keel was found fractured at the bolt holes just forward of the rear engine support mounts. The pilot's contour ABS plastic seat, which also served as the fuel tank was found punctured on its back, with most of the automotive fuel leaking out, with the exception of approximately one gallon. All three blades of the wooden propeller were found fractured and the engine mounts were bent upwards on the right side. Grass and debris were found in the carburetor throat and the air filter was found separated from the base of the carburetor. The throttle was found bent outward in the full open position. The seat was found separated from the airframe. Fuel was found in the fuel lines and the carburetor. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy and toxicology tests were ordered and performed on the pilot. The autopsy was performed by Sheila Spotswood, M.D, of the Southwest Institute of Forensic Sciences in Dallas, Texas, on April 25, 1993. Toxicological findings were negative. SURVIVAL ASPECTS The gyroplane was not equipped with shoulder harnesses. The pilot was wearing a helmet. ADDITIONAL INFORMATION The wreckage was released to the owner's representative on June 22, 1993, upon completion of the field investigation.
THE PILOT'S INADVERTENT PORPOISE. A FACTOR WAS THE IMPROPERLY ADJUSTED TRIM SPRING
Source: NTSB Aviation Accident Database
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