CEN19LA303

The pilot reported that the engine lost power during cruise flight. While troubleshooting, he noticed that the forward carburetor of the dual-carburetor-equipped engine had separated from the intake socket. He subsequently performed a forced landing to a field, during which the left wing spar was substantially damaged. A postaccident examination revealed that the forward intake socket did not conform to an exemplar socket provided by the engine manufacturer. In addition, the intake silencer was not supported except by the carburetors. Maintenance records indicated that the intake silencer was installed before the current owner purchased the airplane. A daily inspection checklist provided by the engine manufacturer included inspection of the sockets and silencer. The in-flight separation of the forward carburetor from the intake socket was likely the result of the improper intake silencer installation, which lacked support other than the forward and aft carburetor intake sockets.

On September 4, 2019, about 1735 eastern daylight time, a Phantom Aeronautics X-1 light-sport airplane, N111JC, was substantially damaged during a forced landing following a loss of engine power near Van Wert, Ohio. The pilot was not injured. The airplane was registered to and operated by private individuals as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed, and the flight was not operated on a flight plan. The local flight originated from the Van Wert County Airport (VNW), Van Wert, Ohio, about 1730. The pilot reported that the engine lost power about 5 minutes into the flight. He noticed that the forward carburetor of the dual-carburetor equipped engine had become separated from the intake socket. He executed a forced landing to a bean field, resulting in damage to the left-wing spar. The pilot reported that he had completed a preflight inspection and did not observe any anomalies. A postaccident examination confirmed that the forward carburetor was separated from the socket. The aft carburetor remained attached to the aft socket and both carburetors remained secured to the intake silencer (airbox). Visual examination did not reveal any other anomalies with respect to the engine assembly. Further examination revealed that the installed socket did not match an exemplar socket provided by the engine manufacturer's representative. Specifically, the installed socket had a step at the end mating to the carburetor inlet which was not present on the exemplar socket. In addition, the intake silencer was not supported except by the forward and aft sockets. There was no independent method of support. The engine installation manual noted that the intake silencer "must not influence the position of the carburetor" and that it needed to be supported accordingly. No further guidance was provided by the manual. Aircraft maintenance records indicated the engine was rebuilt in July 2017 at 948.6 hours airframe total time. The engine total time when rebuilt was 424.0 hours. The air intake silencer was installed in July 2018 at 972.7 hours airframe time (448.1 hours engine time). On April 21, 2019, at 976.4 hours airframe total time (451.8 hours engine time), the spark plugs and carburetor boots were replaced, and the carburetors were synchronized. A condition inspection was also completed at that time. The airplane was sold to the accident owner in June 2019. The final maintenance entry noted replacement of the spark plugs on August 8, 2019, at 1,003.0 hours airframe time (478.6 hours engine time). The engine manufacturer provided operators with a daily and preflight inspection checklist. The daily inspection checklist advised operators to check carburetor sockets for cracks and secure attachment. It also included a check for security and condition of the intake silencer and air filter.