NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot and passenger were on a cross-country personal flight when the pilot noticed oil on the airplane's windscreen. The pilot subsequently landed and had maintenance personnel inspect the airplane. Maintenance personnel noted that the crankshaft seal was leaking and identified several other discrepancies. The pilot chose to have the repairs completed. During the repairs, maintenance personnel noticed that the bolt holding the throttle cable bracket was loose, worn, and not safety wired. The maintenance facility did not have an exact replacement bolt, so the mechanic found a similar bolt, drilled a hole in the bolt head for the safety wire, and installed the bolt. The mechanic installed the safety wire through the throttle bolt and then down to the mixture control bolt. The pilot periodically inspected or observed the work as maintenance personnel finished the repairs on the airplane. The pilot also took a photo of the throttle linkage area, which showed that the safety wire was installed.
After the repairs were completed, the pilot conducted a local test flight. No problems were noted, and the pilot and passenger continued their flight. After an en route fuel stop, the airplane departed and reached 2,300 ft, at which point the engine lost power Although the engine remained at idle, it would not respond to the pilot's throttle inputs. The pilot subsequently conducted a forced landing to a field. Following the forced landing, the pilot re-entered the airplane to ensure that the electrical power and fuel and were off and that there was no fire. He then removed the engine cowling and found the throttle linkage "disconnected or broken."
A postcrash examination of the airplane, revealed that the bolt holding the throttle cable bracket was missing, which had allowed the throttle cable to "float," meaning that manipulating the throttle control from the cabin would not govern the engine's throttle position. The examination also revealed that the mixture control bolt was in place. However, the throttle cable bolt and associated safety wire were not found.