Accident Overview
On April 10, 2020, at about 1225 central daylight time, a Beechcraft N35, registration N1258Z, was substantially damaged during a forced landing near Sidney, Iowa. The airline transport pilot and a passenger were uninjured. The airplane was being operated as a personal flight under Title 14 Code of Federal Regulations Part 91.
Pilot Account
The pilot reported that the accident flight was the third flight following an annual inspection. The airplane had accumulated about 1.5 hours of flight time since the inspection and had been topped off with fuel before departure. Approximately 80 minutes into the cross-country flight, while cruising at 4,500 ft above mean sea level, the engine suddenly stopped producing power. The pilot noted no warning signs and that all engine instruments appeared normal. He attempted to restore power; turning the key to "START" produced a sound consistent with an attempt to start an already running engine. When he moved the throttle from the cruise setting to idle and back, the RPM gauge fluctuated. As the airplane descended to about 1,500 ft msl (1,000 ft above ground level), the pilot began searching for an emergency landing area. At that time, he and his passenger noticed a "slight burning smell."
Unable to reach an airport, the pilot executed an emergency landing to a grass field. Upon touchdown, the airplane encountered uneven terrain, causing the nose gear to collapse and the left main gear to compress upward into the left wing, resulting in substantial wing damage.
Postaccident Examination
During the postaccident examination, thumb compression was observed on all cylinders when the propeller was rotated. The impulse coupler was heard, indicating internal continuity from the front to the back of the engine. Spark plugs were removed and appeared intact and undamaged, though the spark plug manufacturer (Champion and BG) and electrode gaps were inconsistent. The magnetos and wiring harnesses were tested on a bench using a hand drill, and spark was observed on all ignition harness leads.
The propeller governor was examined by an NTSB investigator. A small amount of unidentified metallic material and debris was found on the oil screen but not inside the governor. The governor was disassembled and found to be unremarkable.
The fuel system was examined, and no anomalies or malfunctions were discovered that would have prevented normal operation. Fuel from the gascolator was checked for proper color and for the presence of debris or water, with no contamination found.
Conclusion
The source provides no stated cause for the accident.