Incident Details
During a preflight inspection, the pilot checked the fuel quantity using the wing fuel sight gauges. The left gauge indicated 45 gallons and the right gauge indicated 55 gallons, which the pilot considered sufficient for the planned 1-hour-50-minute cross-country flight. During the flight, both engines lost power, and the pilot ditched the airplane in ocean waters approximately 8 nautical miles short of the destination airport.
Investigation Findings
Examination of the airplane revealed empty fuel tanks. The right wing fuel sight gauge still indicated 55 gallons. The left wing fuel sight gauge initially indicated in the cross-hatched area, but after being jiggled, it indicated 43 gallons. Removal of the fuel sight gauge access plates showed that black felt tip pen marks (hash marks) on the mount plates and on the gauges did not align. The gauges were installed improperly, such that the floats were restricted in their range of travel by the wing structure. When the gauges were rotated to a position where the hash marks aligned, the floats had full range of travel, and both gauges indicated in the cross-hatched (unusable) area.
Maintenance History
Approximately four months before the accident, fuel leaks in the left and right wings were repaired by replacing the right-hand outboard and left-hand inboard leading edge fuel cells. This repair included replacement of both wing fuel sight gauges. According to one of the two mechanics who performed the work, when the sight gauges were removed, they marked them "R" and "L" and made hash marks on the mounting plates. Upon reinstallation, they used the hash marks to return the gauges to their original positions. However, interviews with the airplane's owner and another mechanic provided conflicting information about whether the sight gauges had been repositioned after the repair.
Fuel Quantity Assessment
The pilot's operating handbook states that the fuel sight gauges are to be used for partial filling or off-loading and only when the gauge reads within the calibrated area between 40 and 60 gallons. Information from the airplane's owner and a trip book indicated that at the time of the pilot's preflight, the airplane had been flown 3.9 hours since its last refueling. At the time of the accident, it had been flown 5.5 hours. Using a fuel burn rate of 30 gallons per hour, the airplane would burn 117 gallons in 3.9 hours and 165 gallons in 5.5 hours. Subtracting 117 gallons from the usable fuel capacity of 166 gallons indicated that at preflight, the airplane contained about 49 usable gallons, with about 24.5 gallons in each wing. If the sight gauges had been properly installed, they would have read in the cross-hatched area. The airplane was also equipped with left and right fuel quantity indicators in the instrument panel, but the owner stated these did not work properly and multiple maintenance facilities had been unable to resolve the problem. The owner and family members who flew the airplane, including the accident pilot, used the sight gauges to determine fuel for partial loads.