N644VZDavison Jb VARI EZE · 2008

On June 02, 2008, about 1050 Pacific daylight time, a Davison Vari Eze, N644VZ, crashed in a field near Arlington Municipal Airport, Arlington, Washington. The pilot, who was additionally the owner and builder, was operating the airplane under the provisions of 14 Code of Federal Regulations Part 91. The private pilot, the sole occupant, sustained minor injuries; the airplane sustained substantial damage. The personal local area flight departed from Arlington about 1000. Visual meteorological conditions prevailed, and a flight plan had not been filed.

In a telephone conversation with a National Transportation Safety Board investigator, the pilot reported that the accident flight was the airplane's second flight. As it was to be an introduction flight, he planned to perform maneuvers in the local area and get accustomed to the flight characteristics of the airplane. After 45 minutes aloft, with the airplane adjacent to Mount Vernon, Washington, the tachometer began reading erratically and subsequently failed, reading zero. The pilot opted to return to Arlington and entered the downwind leg of the traffic pattern for runway 16. He turned the airplane (right) onto the base leg and leveled the wings. He glanced down at the tachometer and noted that it indicated 0 rpm, an indication that the gauge was still inoperative.

The pilot further stated that he advanced the throttle forward, but the engine did not respond. The engine had experienced a total loss of power. He selected a field below to land in and the airplane nosed over during the landing roll. The pilot added that during the time of the engine failure the fuel selector was positioned on the main fuel tanks, each of which contained about 4 gallons. The pilot later opined that the loss of engine power was a result of air getting entrapped in the fuel system, as the airplane was not equipped with a fuel pump. He added that during a high-speed taxi test in the early stages of the airplane's testing, the engine had quit as a result of air entering the system.

The airplane was equipped with a Teledyne Continental Motors (TCM) C85 engine, which had a supplemental type certificate (STC) for various upgrades to make it comparable to an O-200. The airplane additionally was configured with an Ellison throttle body and did not have a fuel pump (gravity fed fuel system). The engine was secured for a future teardown examination.

A mechanic examined the wreckage under the auspice of a Federal Aviation Administration (FAA) inspector. The mechanic and FAA inspector reported finding no discrepancies in compression, magneto firing, or fuel system continuity. Manipulation of the cockpit engine controls revealed that when advancing the throttle control, the throttle control outer cable housing would slip out of the throttle quadrant and the throttle arm on the engine fuel body did not move. All other controls would easily move through normal travel. It could not be determined if this discrepancy was a result of the impact.

The Ellison Throttle Body Injector Manual section 2-5, Installation, states a caution of "In the event of any throttle linkage failure allowing unrestrained throttle movement, the engine will immediately and without hesitation, return to idle."