What happened
During cruise flight at 1,8 and00 feet, the aircraft engine shut down while operating from a center tank that was approximately one-third full. At the time of the failure, the front tank was full and the rear tank was nearly empty. The pilot switched the fuel source to the front tank, which allowed the engine to restart after 10 to 15 seconds. However, the engine ran smoothly for only 15 to 20 seconds before shutting down a second time, at which point the fuel pressure reading dropped to zero.
The pilot attempted to restore fuel pressure using a hand-operated wobble pump but was unsuccessful. Consequently, the pilot performed a forced landing on a high school football and baseball field. During the landing, the aircraft skidded across the wet field and struck a 10- to 12-foot-high chain link fence head-on at approximately 30 to 35 MPH. The pilot was not injured.
The investigation
An FAA inspector conducted a post-accident examination of the fuel selector valve and identified anomalies that allowed the valve to aspirate to an empty tank in two distinct ways.
First, when using the wobble pump to create suction in the supply-side line, slight inward pressure on the center of the valve would unseat it, causing an instant loss of prime. Recovery was impossible unless the valve returned to its original position. Second, the inspector found that enough suction could be created while the valve was in the 'off' or intermediate positions to unseat the valve and cause aspiration. This condition was noted to be repeatable, even with a newly overhauled valve.