An ATR42 was dispatched with the right fuel tank quantity indicator deferred as inoperative per the MEL and the wrong dripstick or dripsticks located in the tank.
Synopsis
An ATR42 was dispatched with the right fuel tank quantity indicator deferred as inoperative per the MEL and the wrong dripstick or dripsticks located in the tank.
Narrative
Rewritten in plain English from NASA’s original all-caps telegraphic report — facts, figures, and terminology preserved.
This report involves an MEL on the ATR regarding inoperative fuel gauges. The MEL allows the airplane to be flown for up to 10 days with an inoperative fuel quantity indicator. The alternate system used to determine the actual fuel on board is highly inaccurate.
We were given an airplane to take from EWR to BWI and the right fuel tank gauge was MEL'ed. With help from maintenance we checked the dripstick numbers, checked the chart and then determined we had 2100 lbs in the right tank. We landed at BWI having burned 600 lbs from the right tank. At this point, we should have had 1500 lbs left.
On the ground at BWI we added 80 gallons (536 lbs). At this point the captain and I checked our dripsticks and we both checked the numbers and the charts twice and the sticks indicated just over 1000 lbs. This was a 1000 lb discrepancy in what the fuel sticks said we had and what we thought we had.
So we added another 100 gallons (670 lbs) and 'resticked' the tanks; and now the drip tanks indicated 2100 lbs. Another 400 lb discrepancy. This system is dangerous because you cannot accurately determine the amount of fuel on board. If you have a situation where you cannot take a large amount of fuel because of a high passenger load, and you have 1000 lbs less than what you thought you had, you stand a good chance of running out of fuel. The MEL, if allowed to exist at all, should be limited to one flight to a station where repairs can be made.
Callback conversation with reporter revealed the following info: The reporter stated the problem with the fueling was mainly caused by attempting to fuel using the dripsticks to verify the load and having the wrong stick or sticks installed in the tank. The reporter said the metered fuel from the truck was being used to fuel both tanks and should have been used for only the right until the correct load was metered into the right tank.
Show the original NASA report (verbatim, telegraphic)
THIS RPT INVOLVES AN MEL ON THE ATR REGARDING INOP FUEL GAUGES. THE MEL ALLOWS THE AIRPLANE TO BE FLOWN FOR UP TO 10 DAYS WITH AN INOP FUEL QUANTITY INDICATOR. THE ALTERNATE SYS USED TO DETERMINE THE ACTUAL FUEL ON BOARD IS HIGHLY INACCURATE. WE WERE GIVEN AN AIRPLANE TO TAKE FROM EWR TO BWI AND THE R FUEL TANK GAUGE WAS MEL'ED. WITH HELP FROM MAINT WE CHKED THE DRIPSTICK NUMBERS; CHKED THE CHART AND THEN DETERMINED WE HAD 2100 LBS IN THE R TANK. WE LANDED AT BWI HAVING BURNED 600 LBS FROM THE R TANK. AT THIS POINT; WE SHOULD HAVE HAD 1500 LBS LEFT. ON THE GND AT BWI WE ADDED 80 GALLONS (536 LBS). AT THIS POINT THE CAPT AND I CHKED OUR DRIPSTICKS AND WE BOTH CHKED THE NUMBERS AND THE CHARTS TWICE AND THE STICKS INDICATED JUST OVER 1000 LBS. THIS WAS A 1000 LB DISCREPANCY IN WHAT THE FUEL STICKS SAID WE HAD AND WHAT WE THOUGHT WE HAD. SO WE ADDED ANOTHER 100 GALLONS (670 LBS) AND 'RESTICKED' THE TANKS; AND NOW THE DRIP TANKS INDICTED 2100 LBS. ANOTHER 400 LB DISCREPANCY. THIS SYS IS DANGEROUS BECAUSE YOU CANNOT ACCURATELY DETERMINE THE AMOUNT OF FUEL ON BOARD. IF YOU HAVE A SIT WHERE YOU CANNOT TAKE A LARGE AMOUNT OF FUEL BECAUSE OF A HIGH PAX LOAD; AND YOU HAVE 1000 LBS LESS THAN WHAT YOU THOUGHT YOU HAD; YOU STAND A GOOD CHANCE OF RUNNING OUT OF FUEL. THE MEL IF ALLOWED TO EXIST AT ALL SHOULD BE LIMITED TO ONE FLT TO A STATION WHERE REPAIRS CAN BE MADE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE PROB WITH THE FUELING WAS MAINLY CAUSED BY ATTEMPTING TO FUEL USING THE DRIPSTICKS TO VERIFY THE LOAD AND HAVING THE WRONG STICK OR STICKS INSTALLED IN THE TANK. THE RPTR SAID THE METERED FUEL FROM THE TRUCK WAS BEING USED TO FUEL BOTH TANKS AND SHOULD HAVE BEEN USED FOR ONLY THE R UNTIL THE CORRECT LOAD WAS METERED INTO THE R TANK.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.