Originally Posted by
737Andi
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
Partly correct. If the switch is on, green usually supplies brake pressure, if green hydraulic system is lost the yellow hydraulic system supplies brake pressure, anti-skid and nose wheel steering remain available. And yes, the triple indicator shows brake pressure.
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.
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. Had it on the line already during landing, really a non-issue, simply continue taxying as normal, no action line on the ECAM, no memory items, just a status that advises the pilots to use a landing distance procedure and that antiskid is still available.
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.