SEA03LA154

The experimental aircraft had just departed runway 30, and was about 400 feet above the ground, when it experienced a complete loss of engine power. The pilot then turned toward an empty field where he was going to attempt an engine-out forced landing, but he was unable to reach the field, and the aircraft impacted an orchard of young apple trees just short of the selected field. A post-accident inspection of the aircraft revealed that the screw holding the valve retaining faceplate on the Airflow Performance Purge Valve Assembly had come loose, allowing the valve mechanism to separate from its housing. It was further determined that the subject retaining screw had not been re-safetied after the builder removed the manufacturer-installed safety wire in order to change the angular configuration of the purge valve/flow divider assembly. A review of the Airflow Performance Installation and Service Manual revealed a narrative section stating that if removal of the valve is necessary, to make sure that the purge valve stop/faceplate screw is re-safetied.

On July 26, 2003, approximately 1130 Pacific daylight time, an Experimental Bollinger RV-6A, N272JT, impacted apple trees during an attempted forced landing about one-quarter mile northwest of runway 30 at Pangborn Memorial Airport, Wenatchee, Washington. The commercial pilot and his passenger received serious injuries, and the aircraft, which is owned by a relative, sustained substantial damage. The 14 CFR Part 91 personal pleasure flight, which was departing for Chelan, Washington, was being operated in visual meteorological conditions. No flight plan had been filed.

According to the pilot, he had just departed runway 30, and was about 400 feet above the ground, when the aircraft experienced a complete loss of engine power. The pilot then turned toward an empty field where he was going to attempt an engine-out forced landing, but he was unable to reach the field, and the aircraft impacted an orchard of young apple trees just short of the selected field.

A post-accident inspection of the aircraft revealed that the stop screw holding the valve retaining face plate on the Airflow Performance Purge Valve Assembly had come loose, allowing the valve mechanism to separate from its housing. It was further determined that the subject retaining/stop screw had not been safety wired as required to insure that it would not back out.

During the investigation, it was determined that in May of 2000, the builder had purchased the fuel flow divider and purge valve as one preassembled unit from Airflow Performance. According to Airflow Performance personnel, and the pictures in the Airflow Performance Installation and Service Manual, when such a pre-assembled unit is sent out, the subject valve faceplate retaining screw is safety wired in series with the two purge valve mounting screws. A further inspection of the aircraft revealed that during the installation of the fuel system, the purge valve was removed from its original mounting pad, rotated 90 degrees, and reinstalled on a piece of angle aluminum that had been riveted onto the original mounting pad. In order to make this alteration, the builder had to disconnect the safety wire that ran between the two mounting screws and the valve face plate retaining screw. As found after the accident, the safety wire attached to the two mounting screws was a completed loop that could not have extended to the faceplate retaining screw. In addition, there were no further scars or markings that indicated that the faceplate screw had been separately safetied.

A review of page I-1 of the Airflow Performance Installation and Service Manual, Revision A revealed a narrative section that made the following statement: Notice how the purge valve stop and two mounting screws are lock wired together. If removal of the valve is necessary, make sure to re-lock wire the purge valve stop screw. Failure to do so will result in sudden stoppage of the engine if the screw backs out."