AN H269C'S FUEL SYS INACCURATELY DISPLAYED SUFFICIENT FUEL WHEN IN FACT IT WAS APPROX 10 GALS LOW. PLT LANDED ON A CLOSED ARPT AT FUEL EXHAUSTION.

Narrative

PLANNED PHOTO FLT FROM ZZZ1 VIA ZZZ2; ZZZ3; ZZZ4; ZZZ5 AND BACK TO ZZZ1. ON THE LEG BTWN ZZZ4 AND ZZZ5; THE FUEL GAUGE SHOWED 10 GALS AFTER 1 HR 17 MINS. THE ESTIMATED REMAINING FLT TIME BACK TO ZZZ1 WAS 35 MINS. DUE TO THE FACT THAT THE GAUGE SHOULD INDICATE AT LEAST 16 GALS; THE DECISION WAS MADE TO DIVERT TO THE 14 NM ZZZ. ENRTE THE FUEL QUANTITY DROPPED SIGNIFICANTLY. WHILE APCHING ZZZ IT WAS DISCOVERED THAT THE ARPT WAS CLOSED (RWY PAVEMENT) -- DUE TO THE DISTRESS NATURE THE PIC DECIDED TO LAND ON THE RAMP ANYWAY SINCE NO PERSONS WOULD BE ENDANGERED. AFTER SET DOWN ON THE RAMP THE ENG QUIT DUE TO A LACK OF FUEL. THE LOW FUEL LIGHT DID NOT COME ON PRIOR OR AFTER THE ENG SHUT OFF. COMPUTATIONS: AFTER COMPUTING WT AND BAL; MAX FUEL QUANTITY WAS ESTIMATED TO 30 GALS. MAX GROSS WT WAS LIMITING FACTOR (CAPACITY: 63 GALS IN 2 FUEL TANKS). AFTER CONSERVATIVE ESTIMATING FUEL BURN (13 GPH-REALISTIC: 10 GAL) THE MAX ENDURANCE WAS CALCULATED TO BE APPROX 2 HR 20 MINS (INCLUDING THE 20 MIN RESERVE; ESTIMATED FLT TIME WAS SET TO 1 HR 50 MINS. FINDINGS: DURING THE PREFLT CHK THE FUEL GAUGE SHOWED A REMAINING 20 GAL OF FUEL ALLOTTED BTWN THE FUEL TANKS. ANOTHER 10 GALS WERE ORDERED TO REACH THE DESIRED 30 GALS FOR MAX RANGE. APPARENTLY THE FUEL GAUGE READING WAS HUGELY MISLEADING: AFTER DRAINING BOTH FUEL TANKS AND EVENLY ADDING 2 GALS OF FUEL IN BOTH TANKS RESULTING IN A TOTAL OF 4 GALS; THE GAUGE INDICATED 10 GALS. WHEN A TOTAL OF 30 GALS WAS EVENLY DISTRIBUTED BTWN THE FUEL TANKS; THE GAUGE READ 45 GALS. THE NOT FUNCTIONING LOW FUEL LIGHT CONTRIBUTED TO THE POTENTIAL DANGEROUS SIT.