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Uncommanded Fuel Transfer

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Uncommanded Fuel Transfer

Old 30th Jul 2019, 03:55
  #1 (permalink)  
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Uncommanded Fuel Transfer

Here is an interesting event that happened the other day. Has anybody heard of or had to deal with such a situation.

"During the climb to cruising altitude after the departure from LGAV, the flight crew identified a slight fuel imbalance.
The associated QRH items were executed in an attempt to rectify the issue, however it was
subsequently identified that there was an uncommanded fuel transfer of 2.6 tons per hour from the
L MAIN tank to the CENTER tank. The flight crew decided to divert to London/Heathrow (EGLL),
UK, and declared a PAN PAN as a precaution. The aircraft landed without further incident.
The operatorís maintenance is currently inspecting the aircraft, and will release it back to service
once the issue is fixed."

punkalouver is offline  
Old 30th Jul 2019, 05:13
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That's about 15 gallons per minute if I did my conversion right. That's a pretty big leak - not a leaky coupling o-ring. There are a few things it could be, depending on the airplane model. What model was it? Were they feeding from the center tank at the time or did it start right after center tank runout? The one event I've seen like that was eventually attributed to a center tank pump outlet check valve jammed open at pump shutdown by a piece of debris, allowing some of the output of the main tank pumps on that side to flow backwards through the center tank pump into the center tank
Dave Therhino is offline  
Old 30th Jul 2019, 08:33
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You donít mention an aircraft type, but this would be nigh on impossible on the 737 due to the design of the fuel system. Firstly, the manual defueling valve would have to be open, which is only possible on the ground (you have to open a panel on the wing leading edge and if the valve is open, the panel cannot physically be closed). Also, the centre tank fueling valve switch would have to be open as (only possible when the fueling panel is open) as well as the cross feed (for fuel to transfer from the left wing tank into the center). If the crossfeed was closed fuel would transfer only from the right wing tank (assuming pumps on).
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Old 30th Jul 2019, 09:29
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Certainly on the 737 300 this is possible and the QRH has a drill for it, which if correctly applied in the sim worked well, I never saw it in a real aircraft.
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Old 30th Jul 2019, 11:03
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B767 BTW ?
gearlever is online now  
Old 30th Jul 2019, 18:35
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What type aircraft? I have had something like this happen about once a decade on different aircraft, but there's always been an established procedure to deal with it. Not a huge deal as long as you are able to monitor and maintain balance within limits until you land.
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Old 2nd Aug 2019, 01:28
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Saw a report on this. It was a 767. There wasn't much detail, but fuel transferred via the refueling system, which was inoperative in some way and was supposed to be in a configuration dictated by the MEL. Either a valve failure or a valve locked wrong led to the transfer - the report wasn't clear. It was verified and fixed readily by maintenance.
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Old 21st Feb 2020, 02:54
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I know this thread is a bit old, but I learned more about the cause of the event. The airplane was dispatched with refuel valves locked open in both the main and center tanks, allowing fuel transfer. Boeing subsequently put out a multi-operator message advising operators not to dispatch the airplane with refuel valves locked open.
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