See my previous post - the A/SKID still works but because it has no reference speed due to ADIRU failure it releases brake pressure to limit the deceleration to 1.7 m/sec/sec (2.8 m/sec/sec on latest BSCU standard).
Still standing by for the answer from our engineers/training gurus, so just a couple of thoughts.
- 1.7 m/sec² is the kind of braking that autobrake low results in - and thats pretty close to no braking at all. That could indeed explain the huge factor.
- You say the BSCU limits deceleration to 1.7 m/sec². When all three ADIRUs are off, where does the BSCU get the limiting decelaration reference from?
- I think at least on a dry runway you can achieve a far better deceleration by using alternate braking w/o antiskid (i.e. A/SKID NWS off) as can be seen by the factor of 1.8 for ANTI SKID Fault (A319, Dry Rwy) compared to 2.55 for the IR1+2+3 Fault.
Even more strange that there is no Abnormal Procedure for this fault.
I'll keep u advised.
Regards, MAX