Narrative:

I have been the owner of a C150 for about 5 yrs. I have never relied upon the fuel gauges; as fuel gauges are historically inaccurate. In fact; the right fuel gauge has progressively deteriorated so that it now indicates 3/4 full when empty. It if flapped as inoperative. As the C150 fuel control is either on or off; the left fuel gauge has become the de facto gauge for gross reference. Finding the gauges unreliable; I have come to rely upon the tachometer time as the indicator of fuel status. (The aircraft is equipped with a hobbs meter; but since I have considered the hobbs as 'fat pencil time;' I do not record flight time from it.) because of recent cold WX in the region; I have found it necessary to let the engine warm up on the ground for prolonged periods in order for the oil pressure gauge to enter the bottom of the green arc. On dec/xx/05; I embarked upon a flight from my home base to an airport 14 NM distant where self-service fuel is available and there exists a collegial atmosphere of experimental aircraft builders and 'barnstormer' pilots. My fuel gauge indicated 1/4 full (about 6 gallons) and the tachometer time usage was consistent with that. This should have been adequate fuel for the 10 min trip; with required reserves. However; with the intersection of inaccurate fuel gauges and failure to account for the additional fuel burn during warm-up periods; I found myself 3 gallons of fuel short (the reserves) on short final to the destination airport. The engine stalled and I landed about 300 ft from the landing threshold. The ground was frozen and flat and made an excellent landing surface. I borrowed gas cans from a gentleman at the airport; refueled and inspected the aircraft; did a short/short field takeoff; flew the pattern; landed and completed my fueling mission and returned to home base. These events; as aircraft mishaps often do; represented a 'perfect storm' of circumstances. I knew the gauges were inaccurate but the indication they gave was consistent with the method by which I calculated fuel requirements in the past. What was left out was the additional fuel burn for the warm-ups that does not advance the tachometer time at the same rate the hobbs would. I have set a new limit (2 hours) on the maximum fuel burn before refueling on this aircraft.

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Original NASA ASRS Text

Title: EXPERIENCED BUT COMPLACENT PLT OF C150 FIGURES HE HAS ENOUGH FUEL FOR A 10 MIN FLT FOR REFUELING. HR FIGURED WRONG.

Narrative: I HAVE BEEN THE OWNER OF A C150 FOR ABOUT 5 YRS. I HAVE NEVER RELIED UPON THE FUEL GAUGES; AS FUEL GAUGES ARE HISTORICALLY INACCURATE. IN FACT; THE R FUEL GAUGE HAS PROGRESSIVELY DETERIORATED SO THAT IT NOW INDICATES 3/4 FULL WHEN EMPTY. IT IF FLAPPED AS INOP. AS THE C150 FUEL CTL IS EITHER ON OR OFF; THE L FUEL GAUGE HAS BECOME THE DE FACTO GAUGE FOR GROSS REF. FINDING THE GAUGES UNRELIABLE; I HAVE COME TO RELY UPON THE TACHOMETER TIME AS THE INDICATOR OF FUEL STATUS. (THE ACFT IS EQUIPPED WITH A HOBBS METER; BUT SINCE I HAVE CONSIDERED THE HOBBS AS 'FAT PENCIL TIME;' I DO NOT RECORD FLT TIME FROM IT.) BECAUSE OF RECENT COLD WX IN THE REGION; I HAVE FOUND IT NECESSARY TO LET THE ENG WARM UP ON THE GND FOR PROLONGED PERIODS IN ORDER FOR THE OIL PRESSURE GAUGE TO ENTER THE BOTTOM OF THE GREEN ARC. ON DEC/XX/05; I EMBARKED UPON A FLT FROM MY HOME BASE TO AN ARPT 14 NM DISTANT WHERE SELF-SVC FUEL IS AVAILABLE AND THERE EXISTS A COLLEGIAL ATMOSPHERE OF EXPERIMENTAL ACFT BUILDERS AND 'BARNSTORMER' PLTS. MY FUEL GAUGE INDICATED 1/4 FULL (ABOUT 6 GALLONS) AND THE TACHOMETER TIME USAGE WAS CONSISTENT WITH THAT. THIS SHOULD HAVE BEEN ADEQUATE FUEL FOR THE 10 MIN TRIP; WITH REQUIRED RESERVES. HOWEVER; WITH THE INTXN OF INACCURATE FUEL GAUGES AND FAILURE TO ACCOUNT FOR THE ADDITIONAL FUEL BURN DURING WARM-UP PERIODS; I FOUND MYSELF 3 GALLONS OF FUEL SHORT (THE RESERVES) ON SHORT FINAL TO THE DEST ARPT. THE ENG STALLED AND I LANDED ABOUT 300 FT FROM THE LNDG THRESHOLD. THE GND WAS FROZEN AND FLAT AND MADE AN EXCELLENT LNDG SURFACE. I BORROWED GAS CANS FROM A GENTLEMAN AT THE ARPT; REFUELED AND INSPECTED THE ACFT; DID A SHORT/SHORT FIELD TKOF; FLEW THE PATTERN; LANDED AND COMPLETED MY FUELING MISSION AND RETURNED TO HOME BASE. THESE EVENTS; AS ACFT MISHAPS OFTEN DO; REPRESENTED A 'PERFECT STORM' OF CIRCUMSTANCES. I KNEW THE GAUGES WERE INACCURATE BUT THE INDICATION THEY GAVE WAS CONSISTENT WITH THE METHOD BY WHICH I CALCULATED FUEL REQUIREMENTS IN THE PAST. WHAT WAS LEFT OUT WAS THE ADDITIONAL FUEL BURN FOR THE WARM-UPS THAT DOES NOT ADVANCE THE TACHOMETER TIME AT THE SAME RATE THE HOBBS WOULD. I HAVE SET A NEW LIMIT (2 HRS) ON THE MAX FUEL BURN BEFORE REFUELING ON THIS ACFT.

Data retrieved from NASA's ASRS site as of January 2009 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.