From the press I read that the German minister of foreign affairs stranded with an Airbus A340 in Abu Dhabi, because the flaps or slats would not correctly retract. To return to the airport they had to dump quite a lot of fuel first.

A German news article has a few details.

So what I read was that after the extra landing they had made a test flight, and everything worked OK. Again, there's a German article on that subject.

However when "fueled to the top" (I guess) again, the flaps or slats had a problem to retract again.

So I'd like to ask: What detail of the construction can prevent the flaps or slats to retract when the wing tanks (I guess that's the relevant part) are filled to the top?

Likewise: What's the role of the temperature, meaning: How much does cerosine expand when the temperature rises (like percent per degree Celsius)?

Could the expansion of the fuel be the problem?

  • $\begingroup$ Aviation Safety Network article. A340-313, reg "16✠01" $\endgroup$
    – mins
    Aug 17, 2023 at 11:53
  • $\begingroup$ Unsure about the reference: Should information from here get there, or the other direction? The ASN article has a few facts about the exact plane (its registration number), but my question was generic about the type of plane (A340). $\endgroup$
    – U. Windl
    Aug 18, 2023 at 11:23
  • 1
    $\begingroup$ Sorry for the confusion created, this is to give a link to a page which might be updated with credible elements in the future. It doesn't provide any answer at the moment of course, except the type and the aircraft registration number. Your question is an interesting one $\endgroup$
    – mins
    Aug 18, 2023 at 12:15
  • $\begingroup$ Having a suspect that the fuel expanding with temperature could cause a physical stress on the structure, I "digged out" some numbers: aluminum alloy expands about 22PPM per °C, while petrol expands about 1060PPM per °C. So assuming the fuel comes from some underground tank rather cool, and the plane is standing in the sun, the fuel's temperature would increase by a few °C, but even for 100000 liters of fuel being warmed up by 10°C that would be "only" an increase of 1060 liters, while the tank in the plane might only expand by 22 liters. So there could be a problem... $\endgroup$
    – U. Windl
    Oct 4, 2023 at 9:29
  • $\begingroup$ In a A340, when tanks are full, surge/vent tanks still allow fuel to expand by 2% (equivalent to 20°C increase). Sensors in surge tanks inform the crew when they are wet. Taxi + takeoff alone will have used about 5 tons of fuel anyway. There are overpressure protections and fuel can be jettisoned in flight if required. $\endgroup$
    – mins
    Oct 4, 2023 at 10:26


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