Narrative:

I arrived at the airport the next morning and proceeded to do my preflight of the aircraft. I didn't climb up and check the fuel levels at that time because I knew the aircraft had not been topped off yet. I would visually check fuel levels after the fueling was complete to ensure the tanks were, in fact, topped off and that both fuel caps were secured properly. I finished the preflight, started the engines and taxied for the fuel pump. The tenant started fueling the plane with me observing and making small talk. After he had fueled the right tank, I noticed that he put 23 gals in the tank, which seemed very odd to me. I thought to myself that possibly the tanks had become imbalanced and that the left would take less on. After he finished the entire fueling process, the pump meter read 46.1 gals. We then walked in and I proceeded to pay while the fueler and I continued to talk. He asked me what it held usable fuel, and I told him 48 gals, but that it didn't seem correct because the gauges shown 1/4 full on each tank last night upon arrival. He then stated 'what I put in yours was nothing. A few weeks ago, I had a guy fly in that took on 38.3 gals in a 38 gal system.' I told him that that seemed odd, which he commented that the gentlemen 'must have been running on fumes.' I paid my bill and proceeded onto my next destination, which was projected to get me there in approximately the same amount of time, 4 hours 6 mins estimating 31 gals (total distance: 377.6 NM). This would give me a chance to compare fuel burns. Upon leaving washington ch, (I23, airport identifier) I received an immediate vector to take me down the east and south side of the cincinnati airspace. My original route was to take me directly over the top of cincinnati. This added approximately 20-30 mi onto my planned trip. Then I received another vector around louisville, then on down to my final destination. I had increased my power to make up some time and knew that fuel would not be an issue. About 30 mi north of my destination I received another vector to head due west (my flight line was taking me ssw). Conditions started to deteriorate (unforecasted) so I hit my initial approach fix which was 25 NM northwest of my destination and conditions continued to worsen. I kept the power up in order to get in before it got any worse. I noted that, at that time my tanks were again indicating just above 1/4 tanks on each side. What had been previously forecast to be 5000 ft ceiling and 10+ mi visibility through the WX briefing I had received earlier that morning, 25 mi north of my destination, the automated WX station on savannah hardin airport (destination) was now reporting 7 mi and 2500 ft ceilings. By the time I actually completed the approach and landed, the visibility was down to 2-3 mi and 700 ft ceiling on the clouds. Upon arriving back at the airfield the next morning, I was informed that my plane had been topped off with 40 gals of fuel. I attributed the additional use of fuel, due to increased distance, increased power settings to make up lost time, as well as increased drag due to some ice that I had picked up on my approach into savannah airport (ice had not been forecasted at my time of arrival). The quarter tank indications on the second leg of my flight were more accurate of fuel remaining than it was the previous day as evidence of the 40 gal fill. In review of my preflight planning, periodic checks en route, and verification of gauges in the cockpit, I felt I was never in danger of being low on fuel and that I operated the aircraft in a safe condition. With the fuel readings at 1/4 on each tank over both rtes towards the conclusion of each flight, indicates to me, something is very inaccurate. Whether this is in the fueling at FBO or in the gauges themselves, is yet to be determined.

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Original NASA ASRS Text

Title: A PLT IS CONCERNED ABOUT A FUEL GAUGE DISCREPANCY IN.

Narrative: I ARRIVED AT THE ARPT THE NEXT MORNING AND PROCEEDED TO DO MY PREFLT OF THE ACFT. I DIDN'T CLB UP AND CHK THE FUEL LEVELS AT THAT TIME BECAUSE I KNEW THE ACFT HAD NOT BEEN TOPPED OFF YET. I WOULD VISUALLY CHK FUEL LEVELS AFTER THE FUELING WAS COMPLETE TO ENSURE THE TANKS WERE, IN FACT, TOPPED OFF AND THAT BOTH FUEL CAPS WERE SECURED PROPERLY. I FINISHED THE PREFLT, STARTED THE ENGS AND TAXIED FOR THE FUEL PUMP. THE TENANT STARTED FUELING THE PLANE WITH ME OBSERVING AND MAKING SMALL TALK. AFTER HE HAD FUELED THE R TANK, I NOTICED THAT HE PUT 23 GALS IN THE TANK, WHICH SEEMED VERY ODD TO ME. I THOUGHT TO MYSELF THAT POSSIBLY THE TANKS HAD BECOME IMBALANCED AND THAT THE L WOULD TAKE LESS ON. AFTER HE FINISHED THE ENTIRE FUELING PROCESS, THE PUMP METER READ 46.1 GALS. WE THEN WALKED IN AND I PROCEEDED TO PAY WHILE THE FUELER AND I CONTINUED TO TALK. HE ASKED ME WHAT IT HELD USABLE FUEL, AND I TOLD HIM 48 GALS, BUT THAT IT DIDN'T SEEM CORRECT BECAUSE THE GAUGES SHOWN 1/4 FULL ON EACH TANK LAST NIGHT UPON ARR. HE THEN STATED 'WHAT I PUT IN YOURS WAS NOTHING. A FEW WKS AGO, I HAD A GUY FLY IN THAT TOOK ON 38.3 GALS IN A 38 GAL SYS.' I TOLD HIM THAT THAT SEEMED ODD, WHICH HE COMMENTED THAT THE GENTLEMEN 'MUST HAVE BEEN RUNNING ON FUMES.' I PAID MY BILL AND PROCEEDED ONTO MY NEXT DEST, WHICH WAS PROJECTED TO GET ME THERE IN APPROX THE SAME AMOUNT OF TIME, 4 HRS 6 MINS ESTIMATING 31 GALS (TOTAL DISTANCE: 377.6 NM). THIS WOULD GIVE ME A CHANCE TO COMPARE FUEL BURNS. UPON LEAVING WASHINGTON CH, (I23, ARPT IDENTIFIER) I RECEIVED AN IMMEDIATE VECTOR TO TAKE ME DOWN THE E AND S SIDE OF THE CINCINNATI AIRSPACE. MY ORIGINAL RTE WAS TO TAKE ME DIRECTLY OVER THE TOP OF CINCINNATI. THIS ADDED APPROX 20-30 MI ONTO MY PLANNED TRIP. THEN I RECEIVED ANOTHER VECTOR AROUND LOUISVILLE, THEN ON DOWN TO MY FINAL DEST. I HAD INCREASED MY PWR TO MAKE UP SOME TIME AND KNEW THAT FUEL WOULD NOT BE AN ISSUE. ABOUT 30 MI N OF MY DEST I RECEIVED ANOTHER VECTOR TO HEAD DUE W (MY FLT LINE WAS TAKING ME SSW). CONDITIONS STARTED TO DETERIORATE (UNFORECASTED) SO I HIT MY INITIAL APCH FIX WHICH WAS 25 NM NW OF MY DEST AND CONDITIONS CONTINUED TO WORSEN. I KEPT THE PWR UP IN ORDER TO GET IN BEFORE IT GOT ANY WORSE. I NOTED THAT, AT THAT TIME MY TANKS WERE AGAIN INDICATING JUST ABOVE 1/4 TANKS ON EACH SIDE. WHAT HAD BEEN PREVIOUSLY FORECAST TO BE 5000 FT CEILING AND 10+ MI VISIBILITY THROUGH THE WX BRIEFING I HAD RECEIVED EARLIER THAT MORNING, 25 MI N OF MY DEST, THE AUTOMATED WX STATION ON SAVANNAH HARDIN ARPT (DEST) WAS NOW RPTING 7 MI AND 2500 FT CEILINGS. BY THE TIME I ACTUALLY COMPLETED THE APCH AND LANDED, THE VISIBILITY WAS DOWN TO 2-3 MI AND 700 FT CEILING ON THE CLOUDS. UPON ARRIVING BACK AT THE AIRFIELD THE NEXT MORNING, I WAS INFORMED THAT MY PLANE HAD BEEN TOPPED OFF WITH 40 GALS OF FUEL. I ATTRIBUTED THE ADDITIONAL USE OF FUEL, DUE TO INCREASED DISTANCE, INCREASED PWR SETTINGS TO MAKE UP LOST TIME, AS WELL AS INCREASED DRAG DUE TO SOME ICE THAT I HAD PICKED UP ON MY APCH INTO SAVANNAH ARPT (ICE HAD NOT BEEN FORECASTED AT MY TIME OF ARR). THE QUARTER TANK INDICATIONS ON THE SECOND LEG OF MY FLT WERE MORE ACCURATE OF FUEL REMAINING THAN IT WAS THE PREVIOUS DAY AS EVIDENCE OF THE 40 GAL FILL. IN REVIEW OF MY PREFLT PLANNING, PERIODIC CHKS ENRTE, AND VERIFICATION OF GAUGES IN THE COCKPIT, I FELT I WAS NEVER IN DANGER OF BEING LOW ON FUEL AND THAT I OPERATED THE ACFT IN A SAFE CONDITION. WITH THE FUEL READINGS AT 1/4 ON EACH TANK OVER BOTH RTES TOWARDS THE CONCLUSION OF EACH FLT, INDICATES TO ME, SOMETHING IS VERY INACCURATE. WHETHER THIS IS IN THE FUELING AT FBO OR IN THE GAUGES THEMSELVES, IS YET TO BE DETERMINED.

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.