Narrative:

The incident occurred on the first flight of the day in a float equipped DHC2 which had not been flown since the previous day. I arrived on duty following a day off and proceeded to my plane to prepare for an early departure. The aircraft had been stored for the evening on an inclined ramp. I proceeded to make a visual inspection of the aircraft as well as a cockpit inspection where I verified the paperwork was in order and checked the fuel and oil levels. The fuel gauges showed the front tank full and the center and rear tanks empty. This was what I expected and was consistent with the common practice of an aircraft to have the front tank topped off at the end of the night to be ready for an early dispatch. I also opened the fueling access door to verify that the caps were secure and to look in the front tank. I did not see any fuel in the front tank which is not unusual as the design of the fuel tank and filler neck precludes visual verification of fuel level unless the tank is overfull. There are no approved fuel dipsticks for the DHC2 that I am aware of, again due to the design of the tanks and filler necks. My first flight of the day was to metlakatla, a round-trip time of .4 hours. Adding .5 hours for the fuel reserve gives a fuel requirement of .9 hours. It is common practice to use the DHC2 fuel gauges as a sole means of determining fuel level with the understanding that the accuracy is within 4-6 gals. The gauge could read as low as 28 gals and there would be adequate fuel supply to initiate the flight per 135.209. Having reasonably determined there was more than sufficient fuel, I proceeded with the flight. While taxiing out, the fuel gauge was rechked during the preflight run-up, and it again read full. The flight proceeded to metlakatla harbor without incident. Taxiing away from the dock in metlakatla, I observed that the fuel selector was still selected for the fullest tank, and initiated takeoff. While departing metlakatla seaplane harbor the engine quit at approximately 100 ft AGL causing a forced landing. No damage or injuries occurred. Total flight time was 11 mins. After landing I was able to restart the engine and taxi back to the dock using fuel from the center tank, although it read empty. At this point the front fuel gauge still read full. I deplaned the passenger and immediately called the dispatcher on duty to report the incident. While refueling the aircraft I carefully observed the front fuel gauge. For the first several gals the needle remained on full and wavered slightly, then suddenly jumped to an indication of 9 or 10 gals. Thereafter it accurately reflected the increasing fuel level. The tank took 34.2 gals to fill which gave a gauge reading of approximately 30 gals. I concluded that although the gauge had indicated a full tank, it could not have contained more than 5 or 6 gals. This incident was caused by an intermittent, insidious, instrument malfunction. DHC2 fuel gauges are known in the industry to be relatively inaccurate, usually within +/-4 or 6 gals. I had several reasons to believe the tank was nearly full, and that I had an adequate supply of fuel. I had no reason to believe however, that the gauge could read full when the tank was in fact, nearly empty. The needle itself was behaving normally, moving from the dead position to the full position when switched on, so the needle itself was not stuck. Therefore, the problem appeared to be the sending unit giving a false reading. My determination of fuel quantity present was consistent with company training and was reasonable given the aircraft design. The only other way to determine fuel level in this case would be attempting to add more fuel to the seemingly full tank, however, this is not company policy or a common practice with this type of aircraft. A contributing factor was the fact that the airplane had so little fuel in it. The legal 1/2 hour minimum would have been at least 12 gals. The front fuel tank normally never sees this low of a level in its life and the rheostat style float indicator may have given a false sensing. Another factor was my decisionto believe the gauge. Suggestion: to prevent this type of incident from occurring again it should be standard procedure, when accepting an aircraft for duty that has been fueled or flown previously by another pilot, to positively verify the fuel level in the tank. In the case of the DHC2, this could only be accomplished by filling the front tank to near overflow, regardless of the gauge indication or fuel requirement. This will certainly be my procedure from now on.

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Original NASA ASRS Text

Title: AN ATX BEAVER PLT RUNS OUT OF GAS ON HIS RETURN TRIP TKOF FROM THE LAKE ARPT MTM, AK.

Narrative: THE INCIDENT OCCURRED ON THE FIRST FLT OF THE DAY IN A FLOAT EQUIPPED DHC2 WHICH HAD NOT BEEN FLOWN SINCE THE PREVIOUS DAY. I ARRIVED ON DUTY FOLLOWING A DAY OFF AND PROCEEDED TO MY PLANE TO PREPARE FOR AN EARLY DEP. THE ACFT HAD BEEN STORED FOR THE EVENING ON AN INCLINED RAMP. I PROCEEDED TO MAKE A VISUAL INSPECTION OF THE ACFT AS WELL AS A COCKPIT INSPECTION WHERE I VERIFIED THE PAPERWORK WAS IN ORDER AND CHKED THE FUEL AND OIL LEVELS. THE FUEL GAUGES SHOWED THE FRONT TANK FULL AND THE CTR AND REAR TANKS EMPTY. THIS WAS WHAT I EXPECTED AND WAS CONSISTENT WITH THE COMMON PRACTICE OF AN ACFT TO HAVE THE FRONT TANK TOPPED OFF AT THE END OF THE NIGHT TO BE READY FOR AN EARLY DISPATCH. I ALSO OPENED THE FUELING ACCESS DOOR TO VERIFY THAT THE CAPS WERE SECURE AND TO LOOK IN THE FRONT TANK. I DID NOT SEE ANY FUEL IN THE FRONT TANK WHICH IS NOT UNUSUAL AS THE DESIGN OF THE FUEL TANK AND FILLER NECK PRECLUDES VISUAL VERIFICATION OF FUEL LEVEL UNLESS THE TANK IS OVERFULL. THERE ARE NO APPROVED FUEL DIPSTICKS FOR THE DHC2 THAT I AM AWARE OF, AGAIN DUE TO THE DESIGN OF THE TANKS AND FILLER NECKS. MY FIRST FLT OF THE DAY WAS TO METLAKATLA, A ROUND-TRIP TIME OF .4 HRS. ADDING .5 HRS FOR THE FUEL RESERVE GIVES A FUEL REQUIREMENT OF .9 HRS. IT IS COMMON PRACTICE TO USE THE DHC2 FUEL GAUGES AS A SOLE MEANS OF DETERMINING FUEL LEVEL WITH THE UNDERSTANDING THAT THE ACCURACY IS WITHIN 4-6 GALS. THE GAUGE COULD READ AS LOW AS 28 GALS AND THERE WOULD BE ADEQUATE FUEL SUPPLY TO INITIATE THE FLT PER 135.209. HAVING REASONABLY DETERMINED THERE WAS MORE THAN SUFFICIENT FUEL, I PROCEEDED WITH THE FLT. WHILE TAXIING OUT, THE FUEL GAUGE WAS RECHKED DURING THE PREFLT RUN-UP, AND IT AGAIN READ FULL. THE FLT PROCEEDED TO METLAKATLA HARBOR WITHOUT INCIDENT. TAXIING AWAY FROM THE DOCK IN METLAKATLA, I OBSERVED THAT THE FUEL SELECTOR WAS STILL SELECTED FOR THE FULLEST TANK, AND INITIATED TKOF. WHILE DEPARTING METLAKATLA SEAPLANE HARBOR THE ENG QUIT AT APPROX 100 FT AGL CAUSING A FORCED LNDG. NO DAMAGE OR INJURIES OCCURRED. TOTAL FLT TIME WAS 11 MINS. AFTER LNDG I WAS ABLE TO RESTART THE ENG AND TAXI BACK TO THE DOCK USING FUEL FROM THE CTR TANK, ALTHOUGH IT READ EMPTY. AT THIS POINT THE FRONT FUEL GAUGE STILL READ FULL. I DEPLANED THE PAX AND IMMEDIATELY CALLED THE DISPATCHER ON DUTY TO RPT THE INCIDENT. WHILE REFUELING THE ACFT I CAREFULLY OBSERVED THE FRONT FUEL GAUGE. FOR THE FIRST SEVERAL GALS THE NEEDLE REMAINED ON FULL AND WAVERED SLIGHTLY, THEN SUDDENLY JUMPED TO AN INDICATION OF 9 OR 10 GALS. THEREAFTER IT ACCURATELY REFLECTED THE INCREASING FUEL LEVEL. THE TANK TOOK 34.2 GALS TO FILL WHICH GAVE A GAUGE READING OF APPROX 30 GALS. I CONCLUDED THAT ALTHOUGH THE GAUGE HAD INDICATED A FULL TANK, IT COULD NOT HAVE CONTAINED MORE THAN 5 OR 6 GALS. THIS INCIDENT WAS CAUSED BY AN INTERMITTENT, INSIDIOUS, INST MALFUNCTION. DHC2 FUEL GAUGES ARE KNOWN IN THE INDUSTRY TO BE RELATIVELY INACCURATE, USUALLY WITHIN +/-4 OR 6 GALS. I HAD SEVERAL REASONS TO BELIEVE THE TANK WAS NEARLY FULL, AND THAT I HAD AN ADEQUATE SUPPLY OF FUEL. I HAD NO REASON TO BELIEVE HOWEVER, THAT THE GAUGE COULD READ FULL WHEN THE TANK WAS IN FACT, NEARLY EMPTY. THE NEEDLE ITSELF WAS BEHAVING NORMALLY, MOVING FROM THE DEAD POS TO THE FULL POS WHEN SWITCHED ON, SO THE NEEDLE ITSELF WAS NOT STUCK. THEREFORE, THE PROB APPEARED TO BE THE SENDING UNIT GIVING A FALSE READING. MY DETERMINATION OF FUEL QUANTITY PRESENT WAS CONSISTENT WITH COMPANY TRAINING AND WAS REASONABLE GIVEN THE ACFT DESIGN. THE ONLY OTHER WAY TO DETERMINE FUEL LEVEL IN THIS CASE WOULD BE ATTEMPTING TO ADD MORE FUEL TO THE SEEMINGLY FULL TANK, HOWEVER, THIS IS NOT COMPANY POLICY OR A COMMON PRACTICE WITH THIS TYPE OF ACFT. A CONTRIBUTING FACTOR WAS THE FACT THAT THE AIRPLANE HAD SO LITTLE FUEL IN IT. THE LEGAL 1/2 HR MINIMUM WOULD HAVE BEEN AT LEAST 12 GALS. THE FRONT FUEL TANK NORMALLY NEVER SEES THIS LOW OF A LEVEL IN ITS LIFE AND THE RHEOSTAT STYLE FLOAT INDICATOR MAY HAVE GIVEN A FALSE SENSING. ANOTHER FACTOR WAS MY DECISIONTO BELIEVE THE GAUGE. SUGGESTION: TO PREVENT THIS TYPE OF INCIDENT FROM OCCURRING AGAIN IT SHOULD BE STANDARD PROC, WHEN ACCEPTING AN ACFT FOR DUTY THAT HAS BEEN FUELED OR FLOWN PREVIOUSLY BY ANOTHER PLT, TO POSITIVELY VERIFY THE FUEL LEVEL IN THE TANK. IN THE CASE OF THE DHC2, THIS COULD ONLY BE ACCOMPLISHED BY FILLING THE FRONT TANK TO NEAR OVERFLOW, REGARDLESS OF THE GAUGE INDICATION OR FUEL REQUIREMENT. THIS WILL CERTAINLY BE MY PROC FROM NOW ON.

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.