PLT UNABLE TO USE ALL FUEL ABOARD ACFT. MAKES UNSCHEDULED STOP FOR REFUELING. FUEL VALVE UNDER PLT SEAT IS IN OFF POS; WITH NO ACCESS TO IT UNTIL PARKED ON GND.

Narrative

THE INCIDENT OCCURRED DURING A FLT FROM PHN TO TYS OF APPROX 3 HRS DURATION. AFTER RUNNING EXACTLY 2:20 ON THE MAIN FUEL SUPPLY; WE SELECTED THE AUX FUEL SUPPLY. THE ENG IMMEDIATELY SUFFERED FROM FUEL DEPRIVATION. A SYS CHK PROVIDED NO INDICATION OF THE CAUSE OF THE PROB. THE MAIN FUEL SUPPLY WAS RESELECTED AND THE PROB WAS ELIMINATED. A FUEL CONSUMPTION ANALYSIS INDICATED THAT THE TYS DEST WOULD BE UNACHIEVABLE. I REQUESTED AN IMMEDIATE DEV TO THE NEAREST ARPT (LOZ) TO ELIMINATE THE POTENTIAL FOR FURTHER COMPLICATIONS. THE DEV WAS AUTH AND MADE. THIS ACTION RESULTED IN A SAFE LNDG WITHOUT FURTHER INCIDENT. A THOROUGH ANALYSIS ON THE GND INDICATED THAT AT SOME TIME DURING THIS OR A PRECEDING FLT AN OBJECT OR THE SEAT WHILE BEING INSTALLED BUMPED AND TURNED OFF THE FUEL SUPPLY VALVE TO THE AUX SYS (LOCATED UNDER THE SEAT). WITH THE PROB IDENTED; AN ARPT WITH A MECH AVAILABLE WITHIN 1:15 OF FLYING TIME WE REFUELED THE MAIN FUEL SUPPLY AND PROCEEDED WITHOUT INCIDENT TO AHN. THE MECH ON DUTY AT AHN EXAMINED THE ACFT; CONCURRED WITH OUR DIAGNOSIS AND CERTIFIED THE ACFT AS AIRWORTHY. UPON RETURN TO OUR HOME BASE OF PHN; WE MADE ARRANGEMENTS WITH OUR LCL MAINT SHOP TO INSTALL A PROTECTIVE FLAP OVER THE VALVE TO ELIMINATE THE POTENTIAL FOR THIS HAPPENING AGAIN.