A PA32 IN CRUISE AT 8000 FT DIVERTED DUE TO ENG FAILURE CAUSED BY A LEAKING MAIN TANK SUMP DRAIN RESULTING IN FUEL STARVATION.

Narrative

WE DEPARTED CHARLOTTESVILLE; VA; WITH FULL FUEL IN ALL TANKS AT APPROX XA00Z ENRTE FOR BLUE ASH ARPT (ISZ) CINCINNATI; OH. THE FLT WAS UNEVENTFUL UNTIL XC00Z. WHILE IN CRUISE AT 8000 FT; I EXPERIENCED A LOSS OF ENG PWR THAT I THOUGHT WAS CAUSED BY CARB ICING. FOLLOWING RECOMMENDED EMER PROCS; I SWITCHED TO MY ALTERNATE MAIN FUEL TANK; APPLIED CARB HEAT; AND AUX BOOST PUMP; AND THE ENG MANIFOLD PRESSURE WAS RESTORED. I CONTACTED CHARLESTON ATC TO EXPLAIN THE LOSS OF 600 FT OF ALT. ATC ASKED WHETHER I NEEDED TO LAND IMMEDIATELY. THINKING THAT THE PROB WAS ELIMINATED; I DECLINED TO DIVERT. HOWEVER; THE PROB RETURNED 10 MINS LATER AND THE EMER PROCS FAILED TO RESTORE PWR. I ASKED CHARLESTON ATC TO VECTOR ME TO THE NEAREST ARPT. WHILE CONFIGURED FOR MAX GLIDE; I NOTED THAT THE MANIFOLD PRESSURE HAD DROPPED TO 13 INCHES AND THAT WE WERE SLOWLY LOSING ALT. THE NEAREST ARPT; ASHLAND; KY (DMU); WAS 7 MI AWAY ACROSS THE OHIO RIVER. ALTHOUGH OUR FUEL USAGE WAS NORMAL; I CONCLUDED THAT FUEL STARVATION WAS THE LIKELY CAUSE OF THE PWR LOSS. I THEN SWITCHED TO 1 OF 2 FULL TIP TANKS AND THE ENG REVIVED ALMOST IMMEDIATELY. I CONTINUED TO FOLLOW THE VECTORS ISSUED BY ATC; TOLD THE CTLR THAT I HAD THE RWY IN SIGHT AND WAS ON SHORT FINAL FOR RWY 10. I EXAMINED BOTH MAIN FUEL TANKS AND FOUND THAT THEY WERE TOTALLY DRY. AT DEP; I HAD CALCULATED THAT I HAD 5 HRS OF FUEL ON BOARD; AND AT THE TIME OF THE LNDG AT ASHLAND; I SHOULD HAVE HAD 2 1/2 HRS REMAINING. THE APPARENT CAUSE OF THE FUEL SHORTAGE WAS A LEAK IN THE MAIN SUMP THAT DRAINED FUEL FROM THE MAIN TANKS AS I SWITCHED BTWN THEM EACH HR. WE CONCLUDED THAT THE MAIN SUMP TEST PORT MIGHT HAVE BEEN STUCK IN THE 'OPEN' POS; CAUSING THE INADVERTENT DUMPING OF FUEL. PERSONNEL FROM THE FBO ASSISTED ME IN TRACING POSSIBLE CAUSES FOR THE LEAK. WE FILLED THE TANKS AND LOOKED FOR PHYSICAL SIGNS OF LEAKAGE AT THE TANKS AND AT THE ENG FUEL PUMP AREA.