Narrative:

ATR 42 had right fuel gauge and low level light deferred as per MEL. Right tank would show low and had low fuel light on sometimes. I misfigured the fuel on departure. Very easy to do. Procedures: 1) look at 'units' on magna stick. 2) look at inclinometer to interpret magna stick. 3) convert units on stick to gallons using graph based on #1 and #2 above. 4) convert gallons to pounds. 5) subtract #4 from pounds desired in that wing. 6) convert #5 to gallons and have fueler put that much in. 7) steps #1-4 again to verify. I interpreted gauge as reading -1. Should have been +1, because the wing I was checking was the high wing. The difference on the graph meant I had 800 pounds in that wing versus 1600 pounds. I burned almost that much en route per side. Stick showed dry tank in msn. Had low gauge to low fuel light, but they were deferred. Bad situation. None of our pilots I talked to realized this and they would have read it the same as I did. Callback conversation with reporter revealed the following information: reporter stated that the procedures for this type operation were given at initial qualification and that the manual referencing this procedure is very weak in its presentation. After this incident he went back into the manual and had to work the problem 3 or 4 times to understand where he had erred. He had spoken with 3 or 4 other capts on this subject and got mostly blank stares. The captain that picked up this aircraft from the reporter was presented this situation and had an 'off the wall' answer, again indicating little or no knowledge of this operation by the air carrier's flcs. The reporter added that the crews sometimes do this once or twice a yr and most likely when there are passenger aboard or in bad WX, either event adding to the urgency of the calculations. This inclinometer is located by the hydraulic access panel on the left side of the aircraft by the passenger door, indicating any variance from a wings level position. 1 mechanic said that he never uses that inclinometer, simply jacking the aircraft to a wings level position so as to preclude reading a plus when it should be a minus. Reporter suggests that the MEL not allow a deferral of the fuel gauges or low level lights, since the crews are so prone to misapplying the correction factors and leaving with improper fuel levels. He was asked to confer with his air carrier relative to their operating procedures.

Related reports:

Google
 

Original NASA ASRS Text

Title: AN ATR CAPT MISREAD THE ACFT'S INCLINOMETER VALUES OF A MINUS VERSUS A PLUS WHILE COMPUTING FUEL REMAINING IN THE R WING TANK. THE R FUEL GAUGE AND R LOW LEVEL LIGHT WERE MEL'ED, REQUIRING A MANUAL CALCULATION OF FUEL IN THE R TANK. UPON ARR AT DEST ARPT THE R TANK WAS EMPTY, A NEAR FUEL STARVATION SIT.

Narrative: ATR 42 HAD R FUEL GAUGE AND LOW LEVEL LIGHT DEFERRED AS PER MEL. R TANK WOULD SHOW LOW AND HAD LOW FUEL LIGHT ON SOMETIMES. I MISFIGURED THE FUEL ON DEP. VERY EASY TO DO. PROCS: 1) LOOK AT 'UNITS' ON MAGNA STICK. 2) LOOK AT INCLINOMETER TO INTERPRET MAGNA STICK. 3) CONVERT UNITS ON STICK TO GALLONS USING GRAPH BASED ON #1 AND #2 ABOVE. 4) CONVERT GALLONS TO LBS. 5) SUBTRACT #4 FROM LBS DESIRED IN THAT WING. 6) CONVERT #5 TO GALLONS AND HAVE FUELER PUT THAT MUCH IN. 7) STEPS #1-4 AGAIN TO VERIFY. I INTERPRETED GAUGE AS READING -1. SHOULD HAVE BEEN +1, BECAUSE THE WING I WAS CHKING WAS THE HIGH WING. THE DIFFERENCE ON THE GRAPH MEANT I HAD 800 LBS IN THAT WING VERSUS 1600 LBS. I BURNED ALMOST THAT MUCH ENRTE PER SIDE. STICK SHOWED DRY TANK IN MSN. HAD LOW GAUGE TO LOW FUEL LIGHT, BUT THEY WERE DEFERRED. BAD SIT. NONE OF OUR PLTS I TALKED TO REALIZED THIS AND THEY WOULD HAVE READ IT THE SAME AS I DID. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THE PROCS FOR THIS TYPE OP WERE GIVEN AT INITIAL QUALIFICATION AND THAT THE MANUAL REFING THIS PROC IS VERY WEAK IN ITS PRESENTATION. AFTER THIS INCIDENT HE WENT BACK INTO THE MANUAL AND HAD TO WORK THE PROB 3 OR 4 TIMES TO UNDERSTAND WHERE HE HAD ERRED. HE HAD SPOKEN WITH 3 OR 4 OTHER CAPTS ON THIS SUBJECT AND GOT MOSTLY BLANK STARES. THE CAPT THAT PICKED UP THIS ACFT FROM THE RPTR WAS PRESENTED THIS SIT AND HAD AN 'OFF THE WALL' ANSWER, AGAIN INDICATING LITTLE OR NO KNOWLEDGE OF THIS OP BY THE ACR'S FLCS. THE RPTR ADDED THAT THE CREWS SOMETIMES DO THIS ONCE OR TWICE A YR AND MOST LIKELY WHEN THERE ARE PAX ABOARD OR IN BAD WX, EITHER EVENT ADDING TO THE URGENCY OF THE CALCULATIONS. THIS INCLINOMETER IS LOCATED BY THE HYD ACCESS PANEL ON THE L SIDE OF THE ACFT BY THE PAX DOOR, INDICATING ANY VARIANCE FROM A WINGS LEVEL POS. 1 MECH SAID THAT HE NEVER USES THAT INCLINOMETER, SIMPLY JACKING THE ACFT TO A WINGS LEVEL POS SO AS TO PRECLUDE READING A PLUS WHEN IT SHOULD BE A MINUS. RPTR SUGGESTS THAT THE MEL NOT ALLOW A DEFERRAL OF THE FUEL GAUGES OR LOW LEVEL LIGHTS, SINCE THE CREWS ARE SO PRONE TO MISAPPLYING THE CORRECTION FACTORS AND LEAVING WITH IMPROPER FUEL LEVELS. HE WAS ASKED TO CONFER WITH HIS ACR RELATIVE TO THEIR OPERATING PROCS.

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.