Can anyone help me answer these questions? I’m looking for genuine technical expert replies without huge prolonged discussions if possible. Would be nice to put these scenarios to bed.
Scenario 1 You are flying along with no failures. Fuel in the left tank appears to be a few tonnes higher than the fuel in the right tank for whatever reason. You stick on the fuel x-feed.
If you stick wing x-feed on, what will happen to the fuel levels?
If the pump pressure on one side is greater, will this inhibit x-feed to the that side?
Scenario 2 You discover a fuel leak in engine 2. As per the fuel leak QRH procedure, you shut down engine 2 which stops the leak. As per QRH procedure, wing x-feed as required. You decide to open the x-feed which allows engine 1 to consume fuel from both inner tank 1 and inner tank 2. However, with the x-feed still open, you have been consuming inner tank 2 fuel contents down to a level which triggers the
FUEL R WING TK LO LVL ecam (1100-2520kg) which requires its onside fuel pumps to be switched off if fuel imbalance required providing no leak.
With engine 2 off, will engine 1 still be able to consume fuel from inner tank 2 despite inner tank 2 pumps switched off?
What if there were less than 2 tonnes available in tank 2 (Gravity restriction), will its fuel still be usable via the x-feed?
Will there be restricted reduced flow to engine 1 during x-feed from inner tank 2?
Wing x-feed is required to be open by the ecam, but is this necessary on one engine?
Scenario 3 Similar to scenario 2, you have discovered a fuel leak in engine 2 which has been isolated by switching of engine 2. Due to ETOPS distance, wing x-feed was initially off & engine 1 consumed its inner tank 1 below the quantity of inner tank 2. You decide to use the fuel imbalance QRH procedure.
Is this a safe method to adopt considering turning off pumps on a good side running engine?
Scenario 4 You are flying along at 35000ft and suddenly a
FUEL R WING PUMPS LO PR ecam occurs. Wing x-feed is switched on as per ecam. Pumps on the affected side are switched off. This puts the inner tank 2 into “gravity feeding”. However, wing x-feed is open meaning engine 2 is consuming fuel from inner tank 1.
Is it now necessary to descend to gravity ceiling as engine 2 is still having pressurised fuel sent to the engine from inner tank 1?
Leaving fuel pumps off overtime will de-aerate the fuel which I assume is the reason a gravity ceiling is required. But is this only an issue if you were to use the fuel from the failed tank?
Why is fuel x-feed switched off at gravity ceiling altitude?
Scenario 5 Flying along after scenario 4, with the inner tank 2 fuel pumps in gravity feeding & wing x-feed open, engine 1 suddenly fails. You decide to maintain altitude and overtime, with engine 2 feeding from inner tank 1, tank 1 will deplete its quantity. You decide to apply a fuel imbalance procedure meaning switching off fuel pumps in inner tank 1 too.
With all pumps now off, will engine 2 consume fuel from inner tank 1 with the x-feed open?
Is this configuration only available at gravity ceiling altitude? Could you run the risk of having engine 2 flame out if this occurred at high altitude?
Scenario 6 As per the QRH Fuel imbalance for a failure of the wing x-feed valve, a bank angle can be introduced in order to transfer fuel.
How does this work? What lines is the fuel transferring through?
Wouldn't this happen in all cases when the aircraft is banking or is it associated to having lighter side pumps off?