A320 HYD SYS LO PRESS during long flights.

[eman mandeel]

Hi Guys,

one of our A320s has been faulting Blue SYS HYD LO PRESS , the press drops from 3000psi to 1400psi for about 5 sec then its back to normal till it triggers again, but it only happens during long flights, flight longer than 3 hours and it only appears between one hour to one and half hour before landing. now we have replaced the Blue elec pump, the press switch, done the wiring but the fault keeps coming back, we tried to regenerate the fault on ground but without any luck. the accumulator is perfect.
has anyone of you come a cross this very strange defect?

 

[WKTaylor]

eman mandeel ... notice the dead silence [no response]???

This is a question best-suited for an aircraft maintenance-technician forum, not an engineering forum. There are several [other] websites intended for aircraft maintenance-technicians to discuss issues like this [specific aircraft models and their peculiarities].

As a reminder, Eng-Tips is a website for engineers with technical degrees [aerospace, mechanical, electrical, civil, etc], not to be confused with maintenance-technicians that are often referred to as 'engineers' in Europe, Africa and Asia.


Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[MikeHalloran]

The question leaves me intensely curious; I've seen some weird stuff happen in hydraulic systems, but I lack sufficient experience or familiarity with that fleet to hazard a guess.

If you do find an answer, please come back and tell us what it was.




Mike Halloran
Pembroke Pines, FL, USA

 

[3DDave]

I'm just curious how the problem knows in advance when the plane is going to land.

The 737 rudder failure at least was tied to descent and ultimately a transient thermal response to hot fluid in a valve sitting in a cold soaked valve body. It was tough to diagnose and would never happen in ground testing, requiring simulation of the transient condition.

If I was to guess it would be that the pump was seizing during a similar transient, and that the replacement was made to similar clearances as the original.

In the case of the 737, there was no visible damage to the valve or the valve body.