History of Flight
On February 26, 2009, about 2100 Pacific standard time, an experimental homebuilt Toland/Thornburgh Twin 503SL weight-shift-control power glider, N426MT, impacted terrain following an unintentional takeoff at Zamperini Field Airport (TOA), Torrance, California. The owner/pilot was operating the glider under 14 CFR Part 91. The airline transport pilot sustained serious injuries; the private pilot passenger was killed. The glider sustained substantial damage to the frame and both wings. The planned local personal flight was in the pre-taxi stage. Night visual meteorological conditions prevailed; no flight plan had been filed.
Witnesses reported the glider was parked facing runways 11R/29L between two hangars on the south side of the airport. The owner/pilot was seated in the rear seat; the pilot-rated passenger was in the front seat. After the engine was started, witnesses heard the engine accelerate to full throttle and saw the glider speeding toward a row of parked airplanes. The glider became airborne in a nose-up pitch attitude and nearly struck the parked airplanes. When the glider was about 75 to 100 feet above the ground, it appeared to stall and impacted the ground between the two runways.
The owner/pilot submitted a Pilot/Operator Aircraft Accident Report. He stated the airplane and engine had no mechanical failures or malfunctions during the flight. After preflight, the passenger was seated in the front seat and was shown the function of the steering bar, pedals, brake, and throttle. After engine start, the pilot tested the brakes by depressing the top of the left pedal, then asked the passenger to perform a brake check. Suddenly, the engine rpm increased to what appeared to be full power. The glider accelerated to takeoff speed and flew off the tarmac. Approximately 150 feet north of the glider were several rows of tied-down airplanes. The glider lifted off and climbed so quickly that it flew over the rows of tied-down airplanes. However, since the glider had not completed the pre-taxi checklist and the control bar was still bungee-tied to the down tube, the pilot was unable to maneuver the wing. The glider climbed to approximately 100 feet, stalled, and descended nose-first to the ground in the middle of the airport between the two runways.
Personnel Information
The owner/pilot holds multiple ratings, including a weight-shift-control flight instructor rating with night flying authorization. The purpose of the flight was to maintain his night flight qualification. The pilot-rated passenger in the front seat was not receiving instruction, had never flown in the accident glider before, and was along as a passenger.
Aircraft Information
The accident glider is an experimental homebuilt weight-shift-control power glider, referred to as a "trike." It is steered by two foot pedals in front of each pilot. The foot controls are similar to airplane controls, except when the top of the left pedal is depressed it activates the nose wheel brake. When the top of the right pedal is depressed, it activates the throttle. Pitch and roll are controlled by a "control bar" in front of the front-seated pilot, which maneuvers a large hang-glider wing. The instructor in the back has extension bars that allow maneuvering the control bar. When the control bar is bungee-tied to the down tube, the wing is locked, comparable to control locks on an airplane.
Wreckage and Impact Information
The FAA accident coordinator inspected the wreckage at the accident scene prior to recovery and verified control continuity to all flight controls and the throttle linkage. A bungee cord was noted near the control bar and near the airframe down tube.
Medical and Pathological Information
The Los Angeles County Coroner completed an autopsy on the passenger. The cause of death was determined to be blunt force trauma. Analysis of specimens for the passenger found no volatiles or tested drugs. Tests for carbon monoxide or cyanide were not performed.
Additional Information
In the pilot’s written statement, he recommended that trike pilots should be aware that the engine could experience uncommanded full power at any time after the engine is running. He stated that before the engine is started, and at all times thereafter, the bungee-tie should be removed from the control bar/down tube so the pilot can immediately start flying the trike in the event of an uncommanded full power that causes the trike to unexpectedly take off. He also recommended that both the front and rear pilots should have immediate and unimpeded access to a "kill switch" that would stop the engine in the event of an uncommanded power increase.
According to FAA Advisory Circular AC 20-27F, Certification and Operation of Amateur-Built Aircraft, "Amateur builders are free to develop their own designs or build from existing designs. We do not approve these designs and it would be impractical to develop design standards for the wide variety of design configurations."