Fedex MD11 near Budapest on Mar 23rd 2010, suspected fuel leak

A Federal Express McDonnell Douglas MD-11 freighter, registration N612FE performing freight flight FX-3 from Dubai (United Arab Emirates) to Paris Orly (France) reportedly carrying several hazardeous goods amongst the cargo, was enroute at FL340 about 100nm eastnortheast of Budapest, when the crew suspected a fuel leak due to fuel quantity indications and decided to divert to Budapest. The airplane landed safely on runway 31R about 25 minutes later.

Maintenance engineers identified a faulty fuel quantity indicator.

The NTSB reported on Mar 24th 2010 - giving the registration of the aircraft erroneously as N592FE, which overflew Hungary 2 hours later and landed in Paris Charles de Gaulle -, that the crew received a low fuel indication, declared emergency and diverted to Budapest. On the ground the fuel indication returned to normal. The airplane did not carry hazardeous goods. The Hungarian TSB have initiated an investigation.

The Hungarian TSB reported on Apr 5th 2010, that the airplane - reporting N612FE - suffered the failure of the fuel quantity indicator and performed an overweight landing to runway 31R leading to overheated brakes. Fire services cooled the brakes.

On May 21st 2014 the Hungarian TSB released their final report in Hungarian concluding the probable cause of the occurrence was:

a technical failure of the fuel quantity indicator.

The actions by the crew were appropriate on the basis of the information available. There was no way to not divert given the phase of flight and symptoms when the erroneous data were displayed.

The TSB reported that the aircraft was enroute about 110nm from Budapest when the crew received a low fuel alert and the fuel gauges indicated 15,800 lbs of fuel remaining when according to flight plan they still should have had 60,000 lbs of fuel. The crew worked the related checklists and attempted to rearrange the fuel system in order to restore the fuel quantity indication, however, without change to the indications. The crew therefore declared Mayday and diverted to Budapest. After landing, while taxiing to the apron, the fuel quantity indications slowly returned to normal finally indicating 60,000 lbs of fuel available. A manual cross check confirmed 60,000 lbs on board. The aircraft thus landed about 24,000 lbs over maximum landing weight. The crew did note an overweight landing in the technical log book of the aircraft.

Examination revealed the #2 fuel quantity sensor had produced false indications due to a faulty signal. The sensor was disabled according to minimum equipment list and the aircraft released to service under minimum equipment list requirements. The fuel sensor was further analysed at the airline's maintenance base in Memphis,TN (USA) where faults in the electrical network were identified and corrected.

The TSB analysed that the actions by the crew were appropriate. With the information available the crew had no possibility to verify the actual fuel quantity on board and thus could not establish that the sensor was faulty and could not rule out a possible fuel leak.