Narrative:

Flight was en route approximately 2:45 hours into the flight. A radio call came in from the flight crew reporting a possible fuel leak and that they were diverting to ZZZ2. Report continued as right main was showing approximately 2500 pounds below left and center tank was empty; both engine fuel flows were even through entire flight and that there was no signs of migration. Reviewing the history shows 1 previous for a fuel quantity indication problem which was cleared in ZZZ1 during the previous night maintenance; nothing referencing fuel leak problems. Since the crew had already made the decision to divert; I asked him to recalculate and see if he had the fuel to make ZZZ. He responded that he was 'ok for ZZZ.' at this point the radio patch became unstable and it was necessary to disconnect. I next sent him an ACARS message asking if it was necessary to add trim to maintain level flight. His response back to the dispatcher; via ACARS; was 'none at this time.' after arrival ZZZ it was revealed that on approach; an attempt was made to start the APU which had failed followed shortly after by the right engine shutting down due to fuel starvation. The aircraft was approximately 10000 ft AGL. ZZZ fueling stuck the tanks and found zero fuel in tank with 1900 on fuel gauge. After approximately 2 hours the fqis (fuel quantity indicating system) began working and indication was 850 and sticks agreed. Review of the ZZZ1 departure fuel slip showed ZZZ1 arrival fuel of L-5450/C-700/right-9400 and that no fuel was added to the right tank. Fuel after fueling in ZZZ1 was L-9400/C-8000/right-9400. The tanks were never stuck to confirm the original imbal. Once we spoke to the crew we were able to ascertain that he had received a fuel level low annunciation earlier in the flight but never revealed this to maintenance control or local maintenance until questioned on the ground. The aircraft performed single engine landing in ZZZ without further incident. Callback conversation with reporter revealed the following information: reporter stated this aircraft arrived with a previously deferred and cleared MEL for a fuel quantity indication problem. This fleet type aircraft utilizes a single 'standard electronic module' (sem) for fuel quantity indication. The quantity signals to the wing fueling panel and cockpit gauges are sent via parallel outputs from the sem. So; if one of the fuel indicators goes out; then the other parallel circuit is separate and functional. However; in this case; maintenance troubleshooting after the flight diverted found the faulty fuel tank compensator signal to the 'sem' actually is upstream of the 'sem' output to the parallel circuits. In effect; both wing and cockpit gauges showed the same incorrect quantity readings without any noticeable disagreements between them that would normally indicate a problem. This reporter does question why a magnetic fuel drip stick check of the wing tanks was not previously accomplished. Supplemental information from acn 732035: I was assigned to work aircraft right fuel quantity indication. I follow the procedure to the best of my knowledge and ability. The fuel quantity was checked and rechked. I cleared the item and released the aircraft. These are some of the factors may have contributed to the problem. 1) the aircraft may be improperly fueled prior to departure or the fuel may not have distributed properly by the fueler. 2) I was not trained on MD88 which may have led to a poor interpretation of the item. 3) I was working alone and did not have someone to xchk my work. Things that I could have done to prevent this occurrence. 1) speak to my lead about the corrective action used to clear the item. 2) get training on the aircraft and get more knowledge of the fuel quantity system on MD88.

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Original NASA ASRS Text

Title: A DC-9 ACFT DIVERTED DUE TO LOW FUEL AND FUEL QUANTITY INDICATION PROBLEMS.

Narrative: FLT WAS ENRTE APPROX 2:45 HRS INTO THE FLT. A RADIO CALL CAME IN FROM THE FLT CREW RPTING A POSSIBLE FUEL LEAK AND THAT THEY WERE DIVERTING TO ZZZ2. RPT CONTINUED AS R MAIN WAS SHOWING APPROX 2500 LBS BELOW L AND CTR TANK WAS EMPTY; BOTH ENG FUEL FLOWS WERE EVEN THROUGH ENTIRE FLT AND THAT THERE WAS NO SIGNS OF MIGRATION. REVIEWING THE HISTORY SHOWS 1 PREVIOUS FOR A FUEL QUANTITY INDICATION PROB WHICH WAS CLRED IN ZZZ1 DURING THE PREVIOUS NIGHT MAINT; NOTHING REFING FUEL LEAK PROBS. SINCE THE CREW HAD ALREADY MADE THE DECISION TO DIVERT; I ASKED HIM TO RECALCULATE AND SEE IF HE HAD THE FUEL TO MAKE ZZZ. HE RESPONDED THAT HE WAS 'OK FOR ZZZ.' AT THIS POINT THE RADIO PATCH BECAME UNSTABLE AND IT WAS NECESSARY TO DISCONNECT. I NEXT SENT HIM AN ACARS MESSAGE ASKING IF IT WAS NECESSARY TO ADD TRIM TO MAINTAIN LEVEL FLT. HIS RESPONSE BACK TO THE DISPATCHER; VIA ACARS; WAS 'NONE AT THIS TIME.' AFTER ARR ZZZ IT WAS REVEALED THAT ON APCH; AN ATTEMPT WAS MADE TO START THE APU WHICH HAD FAILED FOLLOWED SHORTLY AFTER BY THE R ENG SHUTTING DOWN DUE TO FUEL STARVATION. THE ACFT WAS APPROX 10000 FT AGL. ZZZ FUELING STUCK THE TANKS AND FOUND ZERO FUEL IN TANK WITH 1900 ON FUEL GAUGE. AFTER APPROX 2 HRS THE FQIS (FUEL QUANTITY INDICATING SYS) BEGAN WORKING AND INDICATION WAS 850 AND STICKS AGREED. REVIEW OF THE ZZZ1 DEP FUEL SLIP SHOWED ZZZ1 ARR FUEL OF L-5450/C-700/R-9400 AND THAT NO FUEL WAS ADDED TO THE R TANK. FUEL AFTER FUELING IN ZZZ1 WAS L-9400/C-8000/R-9400. THE TANKS WERE NEVER STUCK TO CONFIRM THE ORIGINAL IMBAL. ONCE WE SPOKE TO THE CREW WE WERE ABLE TO ASCERTAIN THAT HE HAD RECEIVED A FUEL LEVEL LOW ANNUNCIATION EARLIER IN THE FLT BUT NEVER REVEALED THIS TO MAINT CTL OR LCL MAINT UNTIL QUESTIONED ON THE GND. THE ACFT PERFORMED SINGLE ENG LNDG IN ZZZ WITHOUT FURTHER INCIDENT. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THIS ACFT ARRIVED WITH A PREVIOUSLY DEFERRED AND CLEARED MEL FOR A FUEL QUANTITY INDICATION PROBLEM. THIS FLEET TYPE ACFT UTILIZES A SINGLE 'STANDARD ELECTRONIC MODULE' (SEM) FOR FUEL QUANTITY INDICATION. THE QUANTITY SIGNALS TO THE WING FUELING PANEL AND COCKPIT GAUGES ARE SENT VIA PARALLEL OUTPUTS FROM THE SEM. SO; IF ONE OF THE FUEL INDICATORS GOES OUT; THEN THE OTHER PARALLEL CIRCUIT IS SEPARATE AND FUNCTIONAL. HOWEVER; IN THIS CASE; MAINTENANCE TROUBLESHOOTING AFTER THE FLIGHT DIVERTED FOUND THE FAULTY FUEL TANK COMPENSATOR SIGNAL TO THE 'SEM' ACTUALLY IS UPSTREAM OF THE 'SEM' OUTPUT TO THE PARALLEL CIRCUITS. IN EFFECT; BOTH WING AND COCKPIT GAUGES SHOWED THE SAME INCORRECT QUANTITY READINGS WITHOUT ANY NOTICEABLE DISAGREEMENTS BETWEEN THEM THAT WOULD NORMALLY INDICATE A PROBLEM. THIS REPORTER DOES QUESTION WHY A MAGNETIC FUEL DRIP STICK CHECK OF THE WING TANKS WAS NOT PREVIOUSLY ACCOMPLISHED. SUPPLEMENTAL INFO FROM ACN 732035: I WAS ASSIGNED TO WORK ACFT R FUEL QUANTITY INDICATION. I FOLLOW THE PROC TO THE BEST OF MY KNOWLEDGE AND ABILITY. THE FUEL QUANTITY WAS CHKED AND RECHKED. I CLRED THE ITEM AND RELEASED THE ACFT. THESE ARE SOME OF THE FACTORS MAY HAVE CONTRIBUTED TO THE PROB. 1) THE ACFT MAY BE IMPROPERLY FUELED PRIOR TO DEP OR THE FUEL MAY NOT HAVE DISTRIBUTED PROPERLY BY THE FUELER. 2) I WAS NOT TRAINED ON MD88 WHICH MAY HAVE LED TO A POOR INTERP OF THE ITEM. 3) I WAS WORKING ALONE AND DID NOT HAVE SOMEONE TO XCHK MY WORK. THINGS THAT I COULD HAVE DONE TO PREVENT THIS OCCURRENCE. 1) SPEAK TO MY LEAD ABOUT THE CORRECTIVE ACTION USED TO CLR THE ITEM. 2) GET TRAINING ON THE ACFT AND GET MORE KNOWLEDGE OF THE FUEL QUANTITY SYS ON MD88.

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.