Incident Overview
During an en route flight, the engine began surging. All instruments displayed normal indications except for the manifold pressure and tachometer, which varied as the engine surged. The aircraft subsequently began losing altitude, prompting the pilot to elect a landing on a highway.
Landing and Evasive Maneuver
The pilot landed in front of several cars but was unable to stop before closing on another vehicle that had slowed ahead. To avoid the vehicle, the pilot turned off the highway, went through a ditch, and struck a chain link fence.
Fuel System Examination
Water was found in the fuel system. An examination of the fuel tanks revealed ridges in the bottom of the tanks. The fuel cells were removed, and evidence showed that the ridges were approximately 1/8 inch in height. The fuel cell bladders were originally installed at the time the aircraft was manufactured in 1959.