WPR10LA272

The pilot was repositioning the airplane when the engine lost power. He made a forced landing in a soft field, and the airplane nosed over. An examination of the wreckage revealed a worn wire on one magneto. It is likely that the intermittent grounding of the magneto could have caused the engine to surge and lose power.

On June 1, 2010, about 1129 Pacific daylight time, an Eagle DW-1, N8815U, made an off airport forced landing near Waterville, Washington. The owner was operating the airplane under the provisions of 14 Code of Federal Regulations (CFR) Part 91. The certificated commercial pilot was not injured. The airplane sustained substantial damage to the empennage. The cross-country positioning flight departed Waterville about 1115, with a planned destination of Missoula, Montana. Visual meteorological conditions prevailed, and no flight plan had been filed. The pilot was positioning the airplane for export, when he encountered a loss of engine power. He made a forced landing in a soft field, and the airplane nosed over. A Federal Aviation Administration (FAA) inspector examined the wreckage. He discovered an anomaly with wiring on one magneto. The 'P' lead is a shielded wire with the primary grounding wire inside of the insulator which, in turn, is surrounded with a braided shielding wire. The shielding wire is always grounded. The inner 'P' wire is grounded at the ignition switch when the key is off. In this case the inner 'P' lead and the insulation were broken through. The wire was held together by about 1/3 of the shielding wire. As the air and vibration moved the wire around, it caused the inner 'P' lead to intermittently come in contact with the always grounded shielding wire. In turn, that allowed the magneto to intermittently turn on and off, causing the engine to surge and lose power.