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Airbus hydraulic failure -

Hello,

apologies in advance if this is a stupid question, couldn’t find the answer googling.

was meant to be on an Airbus from Zurich to LHR, pulled back from gate, long wait without going to runway. hydraulic warning light, mechanic called. I could smell what I assume was hydraulic fluid from the front row.
pilot said the issue was in the tail hydraulics- the pump. Mechanic pumped nitrogen in and apparently it just ran right through, I believe the pilot said. So we couldn’t take off obv.

my query is- what’s the effect if this happens in the air? I know a total hydraulic failure would be un-flyable, but what about just one pump like that? Is there enough redundancy from elsewhere? (Sorry not sure the right way to phrase it)

I’m sorry I’m not certain of the airbus type but I think it was a 319, will update here if wrong because it’s the same one this eve

(I’m just interested, I like planes and I’m not sure if the pilot - we’ll have the same guy in a couple hours on a new plane - would be allowed by BA to answer that if I ask:)

It is hard to deliver a remote diagnosis here.

However, all airliners that I am aware of have multiple independent hydraulic systems taking their liquid from dedicated reservoirs, driven by at least two pumps each. On A320 series aircraft, there are three systems in total. Should one of those systems fail, it will still leave the aircraft flyable and only result in some additional considerations and extended checklist work: all the really important systems are taken over by the two remaining systems, other systems have a backup operating mode not requiring hydraulic pressure. For example the landing gear can be extended via gravity extension if needed. If a second system goes, the aircraft will still fly, but there will be various systems offline. One hydraulic system is required to be operating on nearly all types in order to keep flight controls powered. Exceptions include the F70/100 and the DH8-300, those two types still allow the use of the primary flight controls without any hydraulic pressure available. On the Dash, you will only lose the rudder and the flaps.

There are various protections and additional systems included to make the loss of all 3 hydraulic systems extremely improbable, ranging from using different power sources for individual systems to routing the pressure pipes well separated from each other.

However: on the ground, things look different. While the aircraft may be flyable when the system goes in flight, there is normally no reason to depart an airport without having presented such an issue to maintenance and having it rectified. Depending on the exact time the problem rears its head, it may well even be illegal.

Quote:

Originally Posted by Tu.114 (Post 10505721)

thank you! That’s very interesting.
I was curious as to whether it was the kind of problem that would be ‘flyable, but not a situation you’d take off knowing about’ - e.g. a like single engine failure. Or the kind of problem that’d have involved burning off fuel and difficult landings.

it was an Airbus 319, we had the same replacement plane.

The jet with the problem had just landed so I assume whatever failed must have done so very suddenly (for something to be leaking hydraulic fluid, and leaking nitrogen when they tried that ). BA were flying in parts from London to fix it apparently, as we left.