CHI02LA242

The experimental airplane sustained substantial damage during a forced landing to a bean field after a partial loss of engine power during cruise flight. The pilot reported he was flying at 2,400 feet mean sea level when the engine began to run sporadically with large fuel pressure fluctuations. Attempts to restore engine power failed and the pilot executed a forced landing. The inspection of the airplane's flight controls and engine controls revealed continuity with no anomalies. The inspection revealed that the engine driven fuel pump, throttle body, fuel nozzles, fuel flow divider, electric fuel pump, and the magnetos were in good operating condition. A fuel sample was tested and it tested in the normal range with no contamination. During the inspection of the fuel system, approximately one and a half gallons were drained from the quick drain at the bottom of the fuselage before the fuel "slowed to a dribble." The inspection revealed that two drilled-out rivet heads were restricting the fuel line between the main fuel tank and the header tank. Approximately 19 gallons of fuel were drained from the main fuel tank. The inspection revealed that the tank did not have a finger screen installed at the outlet port. The two drilled out rivet heads found in the fuel line had not been used in the construction of the fuel tank and were foreign to the fuel system. The engine was removed from the airframe for an engine run. The engine operated normally at idle power and at full power during the engine run.

On August 10, 2002, at 1700 central daylight time, a Rare Aircraft WACO T-10, N98TW, sustained substantial damage during a forced landing to a bean field, located about 10 miles southeast of Omaha, Nebraska, after a partial loss of engine power during cruise flight. The commercial pilot and two passengers were not injured. The 14 CFR Part 91 flight departed Millard Airport (MLE), Omaha, Nebraska, at 1630 with Wahoo Municipal Airport (AHQ), Wahoo, Nebraska, as the intended destination. Visual meteorological conditions existed at time of the accident. No flight plan was filed.

The pilot reported he was flying at 2,400 feet mean sea level when the engine began to run sporadically. The pilot reported large fuel pressure fluctuations. The pilot's attempts to restore engine power failed. The pilot executed a forced landing to a soybean field. The left landing gear became entangled in the beans and the airplane spun about 190 degrees.

A Federal Aviation Administration (FAA) airworthiness inspector examined the airplane at the Wahoo Municipal Airport. The inspector reported that all flight controls and engine controls exhibited continuity. He tested the fuel system for pressure from the electrical boost pump and it was found to have "adequate pressure" at the throttle body intake port. All fuel nozzles were removed and tested for fuel flow and no anomalies were found. The inspector reported that the engine driven fuel pump, throttle body, fuel nozzles, fuel flow divider, electric fuel pump, and the magnetos were checked and were found to be in "good operating condition." Approximately one gallon of fuel was drained from the lower sump (header tank) fuel line drain valve. It was tested at a laboratory and the lab analysis revealed that the fuel tested in the normal range with no contamination.

The FAA inspector reported that the airplane's fuel tank was drained to prepare the airplane for shipment to a repair facility. He reported that approximately one and a half gallons were drained from the quick drain at the bottom of the fuselage before the fuel "slowed to a dribble." The inspector examined the fuel lines back to the main fuel tank to find the blockage, and he found the line from the main fuel tank to the header tank restricted. He reported that he removed the fuel line and found two drilled-out rivet heads in the fuel line.

He reported that 19 gallons of fuel were drained from the main fuel tank. An inspection of the fuel tank revealed that there were numerous rivet bucktails in the bottom of the tank. The inspection revealed that the tank did not have a finger screen installed at the outlet port.

An inspection of the fuel tank revealed that 12 rivets had sheared from the fuel baffles inside the fuel tank. Eleven rivet bucktails were found in the bottom of the tank. The two drilled out rivet heads found in the fuel line had not been used in the construction of the fuel tank and were foreign to the fuel system.

The engine, a Jacobs R755-B2 with an Aeroflow fuel injection system installed, was removed from the airframe and shipped to the engine manufacturer for an engine run. The FAA Principal Maintenance Inspector who oversaw the engine run reported that the engine operated smoothly at idle power. He reported the engine was operated to full power after warm up, and the engine operated normally.