Anti Skid and Nose Wheel Steering Switch questions
Hi,
I'm unfortunately not sure if I understood the full potential of this switch correctly. Hopefully someone can bring me nearer to this mystery. From what I have read I understood the following. If the switch is "on" the following applies: - Anti Skid is activated - Nose Wheel Steering is possible - green hydraulic system is supplying the brake system (except parking brake which is always supplied by yellow system) If the switch is "off" the following applies: - Anti Skid is deactivated - Nose Wheel Steering is deactivated (some airlines require this during pushback) - yellow hydraulic system is supplying the brake system I hope this is correct so far? I have also understood that in a case of a failure in the green hydraulic system the normal braking system ceases to work and the yellow hydraulic system takes over. When the pilot notices this on the yellow brake accu pressure indicator it is the correct procedure to let the brakes go, then flip the anti skid and nose wheel steering switch and then use the brakes again to stop the plane. Is it correct that the plane looses its ability to steer the noseplane in this situtation? Thanks for bringing some light into these things! Best regards Andi |
Are you talking about the A320?
I had thought that if you lose the brakes, the yellow system does not automatically take over which is why you need to turn the anti skid switch off. It is also my understanding that you would then have no nose wheel steering but you can still steer with differential braking and asymmetric thrust. |
Yes, I'm talking about the A320.
Ok..in this case it makes sense! Thank you! |
Originally Posted by 737Andi
(Post 10756811)
Hi,
If the switch is "on" the following applies: - Anti Skid is activated - Nose Wheel Steering is possible - green hydraulic system is supplying the brake system (except parking brake which is always supplied by yellow system) If the switch is "off" the following applies: - Anti Skid is deactivated - Nose Wheel Steering is deactivated (some airlines require this during pushback) - yellow hydraulic system is supplying the brake system By the way, haven't seen any SOP that requires the switch to be off for push-back, that is what the pin on the nosewheel is there fore, and its status is shown as a line on the ECAM. I have also understood that in a case of a failure in the green hydraulic system the normal braking system ceases to work and the yellow hydraulic system takes over. When the pilot notices this on the yellow brake accu pressure indicator it is the correct procedure to let the brakes go, then flip the anti skid and nose wheel steering switch and then use the brakes again to stop the plane. For a complete loss of braking there is indeed a memory procedure that advises the pilot to release the brake pedals, order the PM to switch off the Antiskid-Nosewheel Steering switch, and once that is done use the brakes again, however check on the triple instrument to stay below 1000 psi brake pressures. Newer planes have an automatic brake pressure reducer, in that case the pilot can stomp as hard as he likes, he won't get more than 1000 psi. And yes, in that case nosewheel steering is lost, differential braking is available. But usually, come to a stop, get a tow truck. |
Hi Denti, thanks for your reply :)
Originally Posted by Denti
(Post 10757855)
Partly correct.
By the way, haven't seen any SOP that requires the switch to be off for push-back, that is what the pin on the nosewheel is there fore, and its status is shown as a line on the ECAM. No. Normal brake failure is basically a non-issue. Alternate brake takes over, braking is a bit more sensitive and autobrake is lost. But that is about it. |
Originally Posted by Denti
(Post 10757855)
By the way, haven't seen any SOP that requires the switch to be off for push-back, that is what the pin on the nosewheel is there fore, and its status is shown as a line on the ECAM.
. |
Originally Posted by 737Andi
(Post 10758202)
Hi Denti, thanks for your reply :)
Reading your post I said exactly the same, or not?? :) Mike Ray (former American Airlines Captain) mentioned this procedure in his A320 check ride book. Is alternate brake then still pressured by green or by yellow system? |
Originally Posted by Denti
(Post 10758452)
Not quite, the part about the yellow system taking over as long as the switch is on providing full service sans the autobrake wasn't in there.
Most likely I'm misunderstanding you :( but I wrote: "I have also understood that in a case of a failure in the green hydraulic system the normal braking system ceases to work and the yellow hydraulic system takes over." One question regarding the following.... No. Normal brake failure is basically a non-issue. Alternate brake takes over, ......... For a complete loss of braking.......... If in both cases the yellow system jumps in..what is the difference between these 2 cases? Thank you!! |
In the second case the yellow system doesn't jump in, that's why you have to turn the switch off, to restore braking. You don't notice because you see pressure on the triple indicator, you notice because the brakes don't work anymore.
|
Originally Posted by AerocatS2A
(Post 10759924)
In the second case the yellow system doesn't jump in, that's why you have to turn the switch off, to restore braking. You don't notice because you see pressure on the triple indicator, you notice because the brakes don't work anymore.
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