WPR09LA219

During a climb to en route cruise, the airplane's engine lost almost all power, and the pilot had to ditch in a river because he was unable to glide back to the departure airport. The power loss was due to a minimum fuel flow command from the fuel control unit as a result of the seizure of the fuel control flyweights. The seizure of the flyweights was due to their contamination with residue from a failed fuel control tachometer drive bearing. The bearing failed due to its preload spacer being machined incorrectly, and due to the failure of the assembling technician to detect the anomaly at the time the fuel control was assembled.

On April 24, 2009, about 1645 Pacific daylight time, an Allumax Epic LT, N653SB, collided with the waters of the Columbia River during a forced landing near Astoria, Oregon. The commercial pilot and his passenger were not injured, but the airplane, which was owned and operated by the pilot, sustained substantial damage. The 14 Code of Federal Regulations Part 91 personal pleasure flight, which was en route to Boeing Field, Seattle, Washington, departed Astoria Regional Airport about eight minutes prior to the accident. The accident occurred in visual meteorological conditions. The pilot filed an Instrument Flight Rules flight plan, but it had not yet been activated at the time of the accident. According to the pilot, he was climbing to his en route cruise altitude when the airplane's Pratt & Whitney PT6-67A turbo-propeller engine suddenly stopped producing power. He therefore immediately turned back toward the airport he departed from, with the intention of making a power-off landing at that location. Immediately after turning back toward the airport, the pilot used the engine restart emergency checklist in an attempt to reestablish engine power, but was unsuccessful in that attempt. As he neared the airport, the pilot realized that he was not going to be able to stretch the glide far enough to reach the runway, so he elected to ditch the airplane in the Columbia River near the shoreline of downtown Astoria. During the ditching attempt, one of the airplane's horizontal stabilizers was partially torn from the airframe. A post-accident teardown of the engine and its accessories determined that the fuel governor flyweights for the Woodward 8063-063 fuel control seized in the overspeed position, resulting in a command to the fuel governor to produce a minimum fuel flow (power roll-back). Further investigation revealed that the overspeed flyweights became seized because they were contaminated with metal particles from the disintegration of the fuel control unit tachometer drive bearing. The bearing was determined to have failed due to the tachometer shaft preload spacer (part number 3256-098) being machined out of parallel at the time of its production, and the failure of the assembling technician to correctly measure/inspect the spacer/bearing assembly at the time the fuel control was assembled.