PARKER, AZ, USA
N96WM
GARDNER E-RACER MARK II
About 15 minutes after departure on a cross-country flight, the pilot reported on the UNICOM that he was inbound to the airport for landing. Witnesses reported seeing the aircraft flying over the departure end of the runway, at approximately 400 feet agl and observed a momentary pitch oscillation as the aircraft entered a steeply banked left turn. The aircraft continued in the turn, descending gradually toward the ground until impact. The witnesses described the engine sounds as 'unusually loud.' The carburetor throttle body was found in a nearly full-open position while the cockpit twist grip throttle control linkage was found separated at a ball swivel fitting. The throttle grip was found separated from the twist grip throttle. The throttle linkage parts were reportedly not aircraft quality materials. The pilot had recorded in a notebook previous trim problems in which he was required to hold constant back pressure to maintain level flight.
On April 4, 1994, about 1400 hours mountain standard time, an experimental home-built Gardner E-Racer Mark II, N96WM, was destroyed by crash impact and postcrash fire while maneuvering in the traffic pattern at the Parker, Arizona, airport. The aircraft was owned and operated by the pilot under 14 CFR Part 91 of Federal Aviation Regulations. Visual meteorological conditions were prevalent at the time and no flight plan had been filed for the operation. The certificated commercial pilot and his passenger sustained fatal injuries. The flight originated from the Avi Suquilla airport at Parker, Arizona, about 1345 on the day of the mishap. The aircraft took off from the Avi Suquilla airport reportedly enroute to Redlands, California. The aircraft had been parked on the transient ramp since April 1, 1994, and had not been refueled before departure. A lineman at the Avi Suquilla airport reported hearing the aircraft's call sign over the UNICOM frequency transmitting a traffic advisory for landing at the departure airport. The lineman was inside the hangar at the time and did not see the aircraft. He did not report anything unusual about the transmission or notice any sense of urgency in the pilot's voice. Witnesses located .8 mile from the crash site, in line with the departure end of the runway, reported seeing the aircraft taking off and climbing on an approximate heading of 190 degrees over the departure end of runway 19 at the Avi Suquilla airport, to what was described as 400 feet above ground level (agl). The witnesses described the engine sound as unusually loud as compared to similar home-builts they had observed operating near the airport in the past. They stated that the engine sound remained constant until impact. Witnesses stated that, as the aircraft reached the end of the runway, the pilot initially rolled into a 30-degree left banked turn which then suddenly increased to 120 degrees. They stated that the pilot appeared to be correcting and had decreased the bank angle to 20 degrees when the aircraft abruptly rolled back into a 90-degree left bank, and began loosing altitude. They described the final attitude of the aircraft just before impact as a 90-degree left bank with the nose pitched down 45 degrees. One witness stated that it appeared to him that the aircraft continued to roll beyond 90 degrees as it disappeared from view. Almost immediately, smoke was reported rising from the accident sight. The witnesses were unable to provide any quantitative estimates of airspeed other than to state that the aircraft appeared to be "going fast". One witness reported surface winds in the vicinity, at the time of the accident, to be from the north at what he estimated to be 25 to 30 mph. He stated that he thought it unusual for the aircraft to be taking off down wind. The longitudinal axis of the wreckage distribution was estimated to be 330 degrees, extending approximately 300 feet in length and 50 feet in width at the widest point. The initial impact site revealed an impact scar that corresponded dimensionally to the left winglet and contained fragments of the left position light. The final position of the aircraft was inverted on an approximate heading of 330 degrees. The aircraft engine, a Lycoming HIO-360 B1A, had been originally manufactured for application in a rotary-wing aircraft. The engine rebuilder who had last performed repair to the engine, reported that there had been no alteration made to the engine at the time he returned it to the owner. After the mishap, the engine was disassembled by a friend of the family who was an experienced aircraft builder. The disassembly revealed the installation of an STC which replaced the rocker arms and push rods. The replacement rocker arms were aluminum with bushed roller bearings. There were no indications of mechanical malfunction; however, several of the rocker arms had been severely melted or distorted in the postcrash fire. The engine accessory section and the flight and engine instruments had been destroyed by crash impact and postcrash fire. The composite airframe was also heavily consumed by fire. Control continuity and trim position were not verified due to impact damage and the displacement and repositioning of the wreckage that occurred during recovery. Both of the wooden propeller blades had separated at the blade hub upon ground impact. Numerous wooden blade fragments were distributed laterally throughout the impact site beyond the initial ground scar. The Allison throttle body carburetor was reportedly found in a nearly full-open position. According to the aircraft designer, the carburetor is not spring loaded and remains in a static position until mechanically displaced by the throttle linkage. The control linkage was found separated at a ball swivel fitting between the throttle body and the twist grip throttle control. The spring loaded metal clip that surrounds the ball joint lacked spring tension. The metal clip was reported to have been found displaced axially from its normal position and also rotated 90 degrees out of position. The ball did not exhibit any deformation or scarring. The throttle grip was found separated from the twist grip throttle, with no obvious signs of impact. The throttle linkage exhibited signs of fire damage on the aft portion, which included the socket joint and clip. There was no evidence of fire damage on the forward portion of the linkage, which included the ball. The throttle linkage parts were not aircraft quality materials according to the designer of the aircraft. The gear system was hydraulically actuated. The left main landing gear showed aft displacement and distortion. The right main gear was found in the wheel well. The nose gear had separated from the aircraft and was found forward and to the right of the initial ground scar. The pilot's notebook on the aircraft was recovered from the wreckage. Entries mentioned trim and pitch problems on the previous flight in which the pilot was required to hold constant back pressure in order to maintain level cruising flight. That notation corresponded with the first flight in which the aircraft had carried a passenger. According to the designer, this trim condition corresponded to a resultant forward CG shift associated with the additional weight of the passenger. The designer of the aircraft also stated that he had discussed with the builder the need for the right wing angle of incidence to be reshimmed to correct a control response lag in banks to the left and lead in banks to the right. A review of the available aircraft records revealed that the aircraft was being flown under a letter of "Operating Limitations Experimental-Amateur-Built" issued by the Federal Aviation Administration on December 22, 1993. Under the terms and conditions of the letter, the aircraft was restricted from conducting flights beyond a 35 nautical mile radius of Redlands airport for a minimum of the first 40 flight test hours. The terms of the letter also restricted the builder from carrying passengers who are not required for the purpose of flight until the minimum flight test hour requirements had been met. An inspection of the pilot's logbook showed that the aircraft had flown a total of 31.5 hours at the time of the mishap.
the failure of the pilot to maintain control of the aircraft while maneuvering in the traffic pattern following a failure of the throttle control. A factor in the accident was a throttle linkage separation after takeoff.
Source: NTSB Aviation Accident Database
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