747 dumping fuel over Sydney?

[Fred Gassit]

Yesterday (29 June) at about 1400 I saw a 747 departing from (im guessing) rwy34L and it looked to be dumping fuel from the left wing only, it was way too much to be an overfull, venting tank. Does anyone know what the problem was? Can you even vent from only one tank? The aircraft continued out of my sight to the northwest misting the countryside with unburnt juice, did anyone else see it or have an explanation?

[*Lancer*]

It's possible to jettison from only one side, but procedurally you wouldn't (can only think of a physical blockage in the right-hand vent as a possible - and very unlikely reason).

If the 747 really was dumping on departure, flying over Sydney, you would have heard about it in the news already...

[HotDog]

Could have been a stuck vent float vave or a blocked vent drain valve causing fuel to spill from the vent surge tank. I have seen this myself once on a QF 747 in climb out of 16R, trailing fuel from the left wingtip as it was passing Cronulla heading south. Stopped after about 30 secs. probably the same aircaft that you saw yesterday; engineering are perhaps not aware of the fault?

[Fred Gassit]

Yeah that sounds likely, it was a very impressive cloud, it wasnt a QF jet though, red and white and really filthy underneath, I wonder how much they lose in that sort of scenario?

[HotDog]

Any fuel in the vent surge tanks is supposed to drain back into the inboard main tanks 2 & 3. However, if for some reason this does not happen, any fuel in excess of 40 USG will exit through the surge tank vent.

[Duff Man]

The freighter you are talking about was informed of the report (a QF FO from memory) ... and replied ops normal.

[Eastwest Loco]

Shame that Duff.

That was a perfect chance for some inventive vectoring and addressing some badly needed urban renewal opportunities in Redfern.

*sigh* Another chance goes begging.:}

Best all

EWL