A320 Brake Insp. Status CAT 3 Single?

[Speedwinner]

Hi guys,

We just had a 320 with one brake Inop. There's a Mel procedure which says we are now limited to cat 3 single. Not sure why is that? The brakes don't generate a ecam message and I looked into the req for cat 3 and those things are all working. Any hints?

[FlyingStone]

With one brake inop, you should not use autobrake as per the MEL.

The aircraft's CAT 2/3 capability for dispatch (MEL) and inflight (ECAM/QRH table) is different.

[Speedwinner]

Sorry don't understand that. Auto brake is no requirement for cat 3 as it is not mentioned in our tables in the qrh. I can fly without auto brake and do a low vis cat 3 dual approach. Despite that the system can't downgrade because of a open brake in flight right?

[EGPFlyer]

Perhaps anti skid related? You need it for automatic rollout

[Amadis of Gaul]

Cat 3 stuff is always a bit of a weird deal. There are so many variables in how people do it that it's hard to answer in your particular case. For instance, we had a possible stuck brake on a 321. It was inspected and found to be serviceable, but the aircraft was downgraded to Cat 1 because the inspection was done by a non-LMP mechanic. Perhaps you're dealing with something similar.

[FlyingStone]

Sorry don't understand that. Auto brake is no requirement for cat 3 as it is not mentioned in our tables in the qrh. I can fly without auto brake and do a low vis cat 3 dual approach. Despite that the system can't downgrade because of a open brake in flight right?

Again, QRH has nothing to do with dispatch requirements. Same as goes for the landing distance, once you've commenced the flight, different rules apply than when you're still in the briefing room.

If you look at the MEL item for the wheel brake, it says CAT 3 DUAL is not available. The item has an operational procedure, which says that you shouldn't use the autobrake for landing.

If you take a further look as to the autobrake item in the MEL, you will see that it also happens to say CAT 3 DUAL is not available, if the autobrake is inop. I doubt that's a coincidence.

[Fursty Ferret]

Makes sense to me. No autobrake means no automatic rollout* (since even careful braking is liable to result in autopilot disconnection through rudder pedal movement on touchdown, particularly in a crosswind).

* Yes, yes, you could technically land on a really long runway with reverse only and not touch the brakes, but the MEL has to cover the most restrictive scenario...

[Escape Path]

As FS said, both items downgrade capability to cat 3 single. If I'm not mistaken you need both A/skid and A/brk to do an autoland.

Furthermore, the QRH list of equipment is to be used only after in-flight failures, not for dispatch.