DRIGGS, ID, USA
N3469B
Beech D35
The pilot reported that while preparing for landing, he turned on to the base leg and reset the mixture, propeller and throttle controls to full forward. At this time the engine experienced a complete loss of power. The pilot attempted to restart the engine with no success. Due to the low altitude, the pilot felt that he could not make it to the runway and opted to land on a dirt road. During the landing roll, the left wing collided with a fence post. Post-crash inspection of the engine found that the spark plugs for two of the cylinders were 'fouled,' and that the piston heads for these cylinders were black and displayed excessive carbon build-up. The fuel metering unit was bench tested. During the test, it was found that at the high RPM setting, both the fuel pump pressure and the fuel flow pressure were excessively out of limits. It was also noted that contamination that appeared to be 'rubber' or a 'gasket-like' material was found on the fuel control valve, and the manifold valve screens. This substance was also found under and around the seat area on the fuel pump. Large amounts of 'particles' were also found inside the pump return fitting.
On July 4, 1998, at 1145 mountain daylight time, a Beech D35, N3469B, registered to and operated by Aeroways Inc. as a 14 CFR Part 91 personal flight, experienced a loss of engine power. The pilot initiated a forced landing to a dirt road near Driggs, Idaho. During the landing roll, the airplane collided with a fence. Visual meteorological conditions prevailed at the time and no flight plan was filed. The aircraft was substantially damaged and the private pilot and his two passengers were not injured. The flight had originated from Pocatello, Idaho, about 45 minutes prior to the accident. In a written statement, the pilot reported that he began to descend from 9,500 feet mean sea level in preparation for landing at the Driggs Airport. The pilot stated that he entered the pattern for runway 21 right, and after turning on base leg, he "reset the power control, prop - mixture and throttle to the full forward position." The pilot stated that the engine then "shut down completely and immediately at this change in controls." The pilot stated that he noted that the fuel pressure was steady at 14 GPH, the quantity of fuel in his selected fuel tank was indicating half full, and he checked the magnetos, however, the engine would not start. At this time, the pilot stated that his altitude had decreased to a point in which he did not feel that he could make it to the runway and opted to set-up for a landing on a dirt road. During the landing roll, the left wing collided with a fence pole. After the wreckage was recovered, the engine was inspected. During the inspection, the crankshaft was found to rotate easily. Accessory gear, rocker arm, and valve train continuity was established. Compression was developed in each cylinder. All spark plugs were examined and found that the plugs for the number one and two cylinders were "fouled." The piston heads for these two cylinders were found to be black with excessive carbon build-up noted. The remaining spark plugs displayed normal operating signatures. Both magnetos produced a spark in firing sequence. Fuel was present to the engine driven fuel pump, the fuel metering unit, and the gascolator. The fuel injectors were unobstructed. The fuel metering unit was removed from the engine and sent to Casper Air Service, Casper, Wyoming, for a bench test. During the test, it was found that at high RPM (2,600 RPM) the fuel pump pressure was 42.5 PSI. The limits for the pump pressure are from 24.7 PSI to 27.7 PSI. At high RPM, the fuel flow pressure was found to be 178 PPH. The limits for the fuel flow pressure are from 123 PPH to 130 PPH. Further inspection of the fuel systems found evidence of contamination that appeared to be "rubber" or a "gasket-like" material on the fuel control valve screen, the manifold valve screen, and under and around the seat area of the fuel pump. A large amount of "particles" were also found inside the fuel pump return fitting.
Excessive pressure in the fuel control unit. A foreign material/substance found on the fuel system screens was a factor.
Source: NTSB Aviation Accident Database
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