PLT OF AN ATX CARGO PIPER PA31 TWIN ENG NAVAJO RAN OUT OF FUEL DURING DSCNT TO LAND AND HAD TO MAKE AN EMER LNDG OFF ARPT RESULTING IN NO DAMAGE TO THE ACFT. WHEN THE ACFT WAS REFUELED IT WAS NOTED THAT THE FUEL GAUGES INDICATED MORE FUEL THAN WAS ACTUALLY IN THE TANK.

Narrative

ENRTE ON A SCHEDULED PART 135 CARGO-ONLY FLT; PLT NOTED RAPIDLY DETERIORATING FUEL QUANTITY INDICATION. PWR WAS REDUCED TO ECONOMY CRUISE SETTINGS. HOWEVER; FUEL STARVATION OCCURRED DURING INITIAL DSCNT TO THE COLD BAY ARPT. AS EACH ENG FAILED; IT WAS FEATHERED; AND AN OFF- ARPT LNDG MADE WITHOUT INCIDENT. DURING APCH; GEAR WAS HAND PUMPED DOWN AND FINAL POS RADIOED TO COMPANY. NO DAMAGE TO THE ACFT OCCURRED. UPON RECOVERY OF THE ACFT IT WAS VERIFIED THAT ALL 4 FUEL TANKS WERE COMPLETELY DRAINED OF USABLE FUEL. HOWEVER; REFILLING THE TANKS WITH A CALIBRATED BUCKET YIELDED QUANTITY INDICATIONS SIGNIFICANTLY IN ERROR. THE MAIN TANKS; WHICH HOLD 56 GALLONS PER TANK; INDICATED 1/4 FULL WITH JUST 5 GALLONS IN EACH; AND 1/2 FULL WITH 15 GALLONS. ALTHOUGH AN ERROR IN JUDGEMENT WAS MADE BY THE PIC RELEVANT TO THE FUEL CARRIED AND THE METHOD OF DETERMINING THAT QUANTITY (LIGHT ACFT FUEL GAUGES); THESE ERRONEOUS READINGS CONTRIBUTED TO THE UNSUCCESSFUL OUTCOME OF THE FLT. IN ACFT IN WHICH A VISUAL DETERMINATION OF FUEL QUANTITY IS IMPOSSIBLE WITH LESS THAN FULL TANKS; IE; LOOKING INTO THE TANK VISUALLY; SUCH AS THE PA31 SERIES; CALIBRATION OF FUEL QUANTITY INDICATORS SEEMS TO BE CRITICAL. CONTRIBUTING FACTORS WERE A SCARCITY OF VIABLE ARPTS TO WHICH TO DIVERT; A SIGNIFICANT HEADWIND; AND THE LACK OF A TIMELY ENOUGH RESPONSE TO A CLRLY WORSENING SIT (EARLIER FUEL CONSERVATION OR DIVERSION EFFORTS).