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B737SFP
22nd Jun 2018, 00:19
Hello guys...

Need some help with a situation I had in the last flight.

During cruise, while checking the SD pages, I discovered that the LEFT Intercell Transfer Valve was in transit (Amber triangle shown)... The FCOM says that there are 2 transfer valves per wing, but AFAIK, there's no way to know if only one, or both transfer are in transit (Open / Close or vice versa)...

Than I asked myself, there's anyway to know if that fuel in the outter tank will be usable?

Looks like the only moment I will get an ECAM for this is at the moment that the transfer valves tries to open but stays in the closed position... I believe that depending on the situation it will be a little to late to discover that I just lost 700kgs !

Also, there wasn't no amber half box in the total FOB indication, nor in the Fuel System Synoptic... But, in this cenario, when would i get this indication? Maybe only when both transfer valves tried to open with no success?

By the way, after landing the transfer valve opened and the fuel was transfered as supposed.
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FlightDetent
22nd Jun 2018, 14:05
What you have there is not completely uncommon. When it happened back home while the AB fleet was relatively new (around 4 years after entry into service) it sent a gentle shockwave through the pilot ranks. Properly reported, the engineers did their job and there never was a concern about the issue again.

Your findings are accurate; as well I seem to remember there are 4 sensors separated into 2 parallel signalling loops. Either one could trigger the opening of the valves.

The fuel incident that freaks me is not an OUTR TK one, but the AF with starvation-induced flame-out, while around 1500 kgs were still displayed on the FQI!

Uplinker
22nd Jun 2018, 16:57
There are two fuel transfer valves between each outer tank and its associated inner tank.

Both transfer valves should open when its associated inner tank gets down to approx 750 kg, and all the transfer valves should shut again at the next refuelling. If one of a pair fails, the other should still operate.

The amber indication occurs when either of a pair of valves on that side is open or partially open. If one valve opens or partially opens in flight, the worst that can happen is that your outer tank fuel drains into the inner tank too early, (which you will be able to see by looking at the contents of each tank on the fuel page), So you can still use all your fuel - the only issue is a loss of wing bending relief.

If both transfer valves on one side fail shut - very unlikely but theoretically not impossible - then you might have 700kg less fuel available at the end of your flight.

In these stupid times of carrying minimum fuel, one would asses the weather, number of runways and traffic flow etc., and if necessary might opt to use some of your diversion fuel to commit to the original destination. If weather or traffic was against you, the loss of 700kg could prompt a pan or mayday call, I would suggest.

B737SFP
26th Jun 2018, 02:10
Hi guys... Sorry for taking so long to reply !

Thanks a lot for your answers. They were pretty helpful...

Its always nice to hear and see the point of view or fellow aviators flying around the globe.

​​​​​​All the best.