Baker, FL, USA
N347CX
ALLAN G PIXLEY THATCHER CX4
The pilot reported that he had just completed an overhaul of the automotive conversion engine that was installed in the experimental amateur-built airplane. Before the day of the accident, the pilot conducted several engine ground runs. During most of the ground runs, the engine would not run smoothly when at the idle throttle setting; however, on the last ground run, the engine ran smoothly at idle. On the day of the accident, the pilot planned to break in the engine during a flight over the airport. After takeoff, while the airplane was climbing to traffic pattern altitude, the pilot felt something dripping onto his leg and decided to perform a precautionary landing. When he pulled the throttle back to idle to initiate a descent, the engine stopped producing power. Unable to restore power to the engine, he elected to execute a forced landing, during which the left wing impacted a tree. Although the pilot did not run the engine after the accident, his postaccident examination of the engine revealed no anomaly that would have precluded normal operation. The atmospheric conditions at the time of the accident were conducive to carburetor icing at glide power; however, the airplane’s engine was at a climb power setting before the pilot reduced the throttle to idle to initiate the descent. Therefore, it is not likely that the loss of engine power was the result of carburetor ice. Since the pilot had just completed an overhaul of the engine and the engine would not run smoothly at idle during several engine ground runs, it is likely that the engine idle setting was misadjusted, which resulted in the engine losing power when the throttle was reduced to idle.
On July 16, 2022, about 0635 central daylight time, an experimental amateur-built Thatcher CX4, N347CX, was substantially damaged when it was involved in an accident near Baker, Florida. The pilot sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he had just completed an overhaul of the automotive conversion engine installed in the airplane. Earlier in the month, the pilot conducted several engine ground runs. During most of the engine ground runs, the engine would not run smoothly when at the idle throttle setting; however, on the last ground run, the engine ran smoothly at idle power while using the left, right, and both ignition sources. On the day of the accident, the pilot planned to break in the engine during a flight over the airport. The engine started normally, although it “hit a rough spot at one point on taxi and low RPM.” He determined that the engine was not fully “warmed up” and continued. After takeoff, while the airplane was climbing to traffic pattern altitude, the pilot felt something dripping onto his leg, thought it was fuel, and decided to perform a precautionary landing rather than continue the climb to pattern altitude. When he pulled the throttle back to idle to initiate a descent, the engine stopped producing power. Unable to restore power to the engine, he navigated toward the airport; however, the airplane was unable to reach the runway. The pilot selected a field just short of the airport for a forced landing and during the landing the left wing contacted a tree, which resulted in the right wing and the nose impacting the ground. Examination of the wreckage by a Federal Aviation Administration inspector revealed that the main wreckage came to rest in a nose-down attitude at the edge of a road. Both wings and the fuselage sustained substantial damage. The pilot later determined that it was likely condensation and not fuel that was dripping on his leg after departure. Although the pilot did not run the engine due to propeller damage, his postaccident examination of the engine revealed no anomaly which would have precluded normal operation. Furthermore, he reported that the loss of engine power could have been due to the “idle setting” or carburetor icing. At the time of the accident, the temperature and dew point at a weather reporting facility 9 nautical miles southeast of the accident site were both 73.4° F, with a relative humidity of 100%. These atmospheric conditions were conducive to carburetor icing at glide power.
The improper engine idle setting, which resulted in a total loss of engine power when the pilot reduced the throttle to idle to initiate a descent.
Source: NTSB Aviation Accident Database
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