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JIC
5th Oct 2007, 20:32
Hi.
Could anyone out there explain why it is one will have a complete hyd failure if both systems are low level ?
Is it because there is not enough fluid to create the required pressure ?
or
Is it the lack of fluid which will end up not being suffecient for all the systems to operate?
Thanks for your answer.
Jic.

Clandestino
5th Oct 2007, 21:46
Eeerm... yes and partially yes. Lack of fluid will end up not being sufficient for each and every system to operate within seconds. It's not type specific, any hydraulic system (be it installed in aircraft or any other machine) can not work if there's no hydraulic fluid to transmit the pressure.

If you get both hyd tank compartments low level, only hydraulically operated system left will be emer/parking brake, powered by its own hydraulic acumulator. As far as I remember from my TLS sim sessions, as long as you can find 2500m of runway to land on, it's no big deal.

dann1405
10th Oct 2007, 23:40
As Clandestino says, the first part of your question is really not type specific. Have a think about how hydraulic systems work (this may invlove revisiting those dreaded ATPL manuals!). I think you'll answer your own question pretty quick.

And yes the Emergency Braking will be the only remaining system, as although it is part of the Blue system, once through the non-return valve it almost behaves as an independent system (although can no longer be replenished in this instance of course). This, according to Mr ATR, will leave you with "at least 6 braking applications." Not sure how much I believe that but I hope never to put it to the test in anger :E

Regards
D