Narrative:

En route to dfw I had switched from outboard to inboard tanks when they indicated about 1/2 full. At dfw we topped the inboard tanks (53 gals usable each) and assumed the outboard tanks had at least 15 gals each (38 gals usable tanks). We filed IFR to gulfport, a distance of about 430 NM. At 180 KTS this would take 2.4 hours. Estimated fuel on board approximately 136+ gals. Fuel flow gauges on the trip to dfw had been reading 18-19 gals/hour when at altitude, with engines leaned to give egt readings of 1400-1450 degrees. To be conservative, I used 20 gpm each side in planning dfw to gulfport: 136/40 = 3.4 hours. Ample reserve, I thought, for a 2.4 hour flight. Since this was my first long distance x-country flight in my new plane, I asked a friend (a commercial pilot familiar with the plane)to go with me on the trip. We departed dfw on inboard tanks and switched to outboard when in level flight. I ran on them until they indicated a little less than 1/8 remaining and switched to inboard. Approximately 90 mi from gpt I expressed concern at the fuel gauges showing close to 1/8 remaining. My copilot asked me about my calculations and stated that I should have been using 24-25 gph fuel burn per his experience with the plane. The gauges were obviously not reading correctly. After some quick calculations, we decided we should pick an alternate stop for fuel. While checking the charts, the right engine began to sputter. I switched the right engine to outboard tank assuming there was still a little fuel in it. I gave control of the plane to first officer while I set up the plane for the ILS approach at hammond, la, which by then was about 10-15 mi to our south. First officer stated to center that 'we had a potential engine problem,' and requested priority for the approach, and asked if there was any other traffic. No emergency was declared since we figured we still had at least 20 mins of fuel remaining. We shot the ILS at hammond and taxied to the FBO with both engines still running. I had all tanks topped and took off for tpa. I was airborne several mins before it hit me that we had just put 184 gals of fuel on board and the placards indicated only 182 gals usable! My plane is on lease-back to a commercial carrier and has never been squawked for fuel flow problems. The way these gauges are calibrated or the way they get their data is obviously a problem. That combined with slightly inaccurate fuel tank gauges could have precipitated a more serious result to the situation. Conclusion: never rely on just gauges. Rather use specification charts, experience, etc as confirmation backups for calculations. Plane is currently squawked 'down' until panel is recalibrated.

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Original NASA ASRS Text

Title: ACFT LANDS AT NEAREST ARPT AS PLT REALIZES THAT THEY ARE SHORT OF FUEL AND 1 ENGINE IS CUTTING OUT.

Narrative: ENRTE TO DFW I HAD SWITCHED FROM OUTBOARD TO INBOARD TANKS WHEN THEY INDICATED ABOUT 1/2 FULL. AT DFW WE TOPPED THE INBOARD TANKS (53 GALS USABLE EACH) AND ASSUMED THE OUTBOARD TANKS HAD AT LEAST 15 GALS EACH (38 GALS USABLE TANKS). WE FILED IFR TO GULFPORT, A DISTANCE OF ABOUT 430 NM. AT 180 KTS THIS WOULD TAKE 2.4 HRS. ESTIMATED FUEL ON BOARD APPROX 136+ GALS. FUEL FLOW GAUGES ON THE TRIP TO DFW HAD BEEN READING 18-19 GALS/HR WHEN AT ALT, WITH ENGS LEANED TO GIVE EGT READINGS OF 1400-1450 DEGS. TO BE CONSERVATIVE, I USED 20 GPM EACH SIDE IN PLANNING DFW TO GULFPORT: 136/40 = 3.4 HRS. AMPLE RESERVE, I THOUGHT, FOR A 2.4 HR FLT. SINCE THIS WAS MY FIRST LONG DISTANCE X-COUNTRY FLT IN MY NEW PLANE, I ASKED A FRIEND (A COMMERCIAL PLT FAMILIAR WITH THE PLANE)TO GO WITH ME ON THE TRIP. WE DEPARTED DFW ON INBOARD TANKS AND SWITCHED TO OUTBOARD WHEN IN LEVEL FLT. I RAN ON THEM UNTIL THEY INDICATED A LITTLE LESS THAN 1/8 REMAINING AND SWITCHED TO INBOARD. APPROX 90 MI FROM GPT I EXPRESSED CONCERN AT THE FUEL GAUGES SHOWING CLOSE TO 1/8 REMAINING. MY COPLT ASKED ME ABOUT MY CALCULATIONS AND STATED THAT I SHOULD HAVE BEEN USING 24-25 GPH FUEL BURN PER HIS EXPERIENCE WITH THE PLANE. THE GAUGES WERE OBVIOUSLY NOT READING CORRECTLY. AFTER SOME QUICK CALCULATIONS, WE DECIDED WE SHOULD PICK AN ALTERNATE STOP FOR FUEL. WHILE CHKING THE CHARTS, THE RIGHT ENG BEGAN TO SPUTTER. I SWITCHED THE RIGHT ENG TO OUTBOARD TANK ASSUMING THERE WAS STILL A LITTLE FUEL IN IT. I GAVE CONTROL OF THE PLANE TO F/O WHILE I SET UP THE PLANE FOR THE ILS APCH AT HAMMOND, LA, WHICH BY THEN WAS ABOUT 10-15 MI TO OUR S. F/O STATED TO CENTER THAT 'WE HAD A POTENTIAL ENG PROB,' AND REQUESTED PRIORITY FOR THE APCH, AND ASKED IF THERE WAS ANY OTHER TFC. NO EMER WAS DECLARED SINCE WE FIGURED WE STILL HAD AT LEAST 20 MINS OF FUEL REMAINING. WE SHOT THE ILS AT HAMMOND AND TAXIED TO THE FBO WITH BOTH ENGS STILL RUNNING. I HAD ALL TANKS TOPPED AND TOOK OFF FOR TPA. I WAS AIRBORNE SEVERAL MINS BEFORE IT HIT ME THAT WE HAD JUST PUT 184 GALS OF FUEL ON BOARD AND THE PLACARDS INDICATED ONLY 182 GALS USABLE! MY PLANE IS ON LEASE-BACK TO A COMMERCIAL CARRIER AND HAS NEVER BEEN SQUAWKED FOR FUEL FLOW PROBS. THE WAY THESE GAUGES ARE CALIBRATED OR THE WAY THEY GET THEIR DATA IS OBVIOUSLY A PROB. THAT COMBINED WITH SLIGHTLY INACCURATE FUEL TANK GAUGES COULD HAVE PRECIPITATED A MORE SERIOUS RESULT TO THE SITUATION. CONCLUSION: NEVER RELY ON JUST GAUGES. RATHER USE SPEC CHARTS, EXPERIENCE, ETC AS CONFIRMATION BACKUPS FOR CALCULATIONS. PLANE IS CURRENTLY SQUAWKED 'DOWN' UNTIL PANEL IS RECALIBRATED.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.