Beech 35-A33 — Cambridge, OH

What happened

The pilot was conducting a ferry flight after the engine was disassembled, inspected, and reinstalled following a wheels-up landing incident that occurred a few months before the accident. About 51 minutes after takeoff the pilot declared an emergency with the air traffic controller due to a loss of engine power and stated that the airplane did not have sufficient altitude to land at the nearest airport. The pilot maneuvered the airplane to land in a nearby field, but he was unable to touch down before the end of the field where the airplane impacted trees a few feet above the ground in a level pitch attitude.

Several witnesses reported seeing the airplane flying at a low altitude with a noticeable engine issue. Some of these witnesses reported hearing the engine "sputtering" or "misfiring" before the airplane descended out of their sightline behind trees. One witness reported seeing a “noticeable but faint, wispy, transparent film” trailing the aircraft and “white or light gray puffs” near the exhaust.

According to recorded engine monitor data, during takeoff and initial climb, the fuel flow was 22 to 23 gallons per hour (gph), which was consistent with the airframe manufacturer’s engine performance charts at rated horsepower and manifold pressure. However, as the flight continued, the fuel flow increased to 29 to 30 gph, which was more than double the expected fuel flow for a leaned engine operating at 75% power during cruise flight.

About 41 minutes into the flight, the No. 3 cylinder exhaust gas temperature (EGT) and cylinder head temperature (CHT) began decreasing and at a higher rate when compared to the other cylinders. Similarly, about 4 minutes before the accident, the No. 5 cylinder EGT/CHT also decreased and was inconsistent with the remaining four cylinders.

Postaccident examination of the airplane revealed fuel streaks emerging from a louvered vent and access panel at the lower right side of the engine compartment, continuing aft along the lower right fuselage. There was no evidence of pooling or fuel streaking on the internal surfaces of the engine cowling. The fuel lines forward of the firewall exhibited no evidence of fuel leaks or obstructions, and all fractured fuel line fittings exhibited features consistent with impact related damage.

The No. 3 cylinder head exhibited fuel stains on several cooling fins located on the forward-facing side of the intake port; however, there were no apparent cracks or fuel stains around the fuel injector nozzle or spark plug ports, and the No. 3 fuel injector line did not exhibit any damage or leaks. The No. 3 intake flange gasket compression faces were flattened around the inner diameter hole and there were no apparent kinks or tears. The No. 3 cylinder intake elbow and cylinder intake port flange face did not exhibit any fuel stains. The inter-cylinder baffle between the No. 3 and 5 cylinders exhibited prominent fuel straining and streaking. The remaining cylinders and engine components did not exhibit any visible fuel stains. The postaccident engine examination did not reveal a mechanical failure that would have prevented normal operation.

Based on the excessive fuel flow and engine operation irregularities with the Nos. 3 and 5 cylinders during the flight, the fuel stains on the No. 3 engine cylinder near the intake, and the fuel streaks on the inter-cylinder baffle and the lower right side of the fuselage, the loss of engine power was likely due to a fuel injection system leak at or near the No. 3 cylinder.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.