cricri
Posts: 540
Joined: Sat Oct 02, 1999 12:10 am

Bscu On Airbuses

Thu Mar 01, 2001 2:43 am

just to be sure : BSCU means "Brake System Control Unit"?
Thanks for any reply.
 
A320FO
Posts: 209
Joined: Wed Oct 25, 2000 12:28 am

RE: Bscu On Airbuses

Thu Mar 01, 2001 2:59 am

Cricri,
you almost got it right. BSCU: "Brake and Steering Control Unit"

It controls the nosewheel steering and the brakes. This one unit is composed of two channels (BSCU1/BSCU2). The two channels are functionally the same, just being supplied by AC1, DC1 or AC2, DC2 bus, respectively.

A320FO
 
dc10hound
Posts: 460
Joined: Fri Dec 15, 2000 4:18 pm

RE: Bscu On Airbuses

Thu Mar 01, 2001 5:21 am

Cricri is correct, as far as the Airbus A300 is concerned.
BSCU is the acronynm for the Brake System Control Unit. It controls the anti-skid system, auto-brakes and automatic inflight braking during gear retraction. It is built by Messier-Hispano-Bugatti, and is a real pain.

I don't know about other Airbus aircraft, but this unit has absolutely nothing to do with nosewheel steering on the A300. Steering on that aircraft is completely hydro-mechanically controlled (cables and hydraulics).
Anything else from Airbus and Messier would be scary.
 Wow!
"Eagles soar. But weasels never get sucked into jet intakes.."
 
A320FO
Posts: 209
Joined: Wed Oct 25, 2000 12:28 am

RE: Bscu On Airbuses

Thu Mar 01, 2001 5:43 am

Yeah, seems like both of us are right.....
On the A320 it controls the steering also, its STEER BY WIRE!! Same probably goes for the A330/A340.
Interesting point: If you are in the emergency electrical config, no more steering is available, so the aircraft's direction has to be controlled by differential braking and will have to be towed off the runway.

A320FO
 
dc10hound
Posts: 460
Joined: Fri Dec 15, 2000 4:18 pm

RE: Bscu On Airbuses

Thu Mar 01, 2001 1:27 pm

STEER BY WIRE!!  Wow!
I would love to see that on a ASM (Aircraft Schematic Manual) diagram, and how they really managed to do that. I guess if you're gonna fly by wire, ya might as well steer by wire too! Brrr....

(What's really the problem with just using cables, Airbus?)

A320FO, Can ya give us some more info on how nosewheel steering is done on the other Airbus A/C? I find this concept intriguing.....

And probably would make lots of money troubleshooting it. Smokin cool

With out knowing Airbus FBW A/C, I would guess the BSCU (Brake and Steering Control Unit) on the A320 is set up to translate rudder pedal deflection inputs to the nosewheel steering. Does this A/C have a Tiller? If so, does it mechanically connect to the steering system, or send it's commands to the BSCU?
"Eagles soar. But weasels never get sucked into jet intakes.."
 
A320FO
Posts: 209
Joined: Wed Oct 25, 2000 12:28 am

RE: Dc10hound

Thu Mar 01, 2001 3:45 pm

Here you go:

....A hydraulic actuating cylinder steers the nose wheel. The green hydraulic system supplies pressure to the cylinder, and electric signals from the Brake and Steering Control Unit (BSCU) control it.
The BSCU recieves orders from:
- the Captain's and the First Officer's steering hand wheels (orders added algebraically)
- the rudder pedals
- the autopilot (...rollout during autoland approaches...)
The BSCU transforms these orders into nose wheel steering angle....


The nosewheel steering angle is limited with increasing speed, no matter what control deflection is commanded in the cockpit.

As I am just a pilot, not a mechanic, I can't comment on system maintenance. But I can imagine this system's setup being simpler, as there are no cables running around, passing thru pressure bulkheads and so on. Again, being the user, I haven't made any negative experiences yet.


A320FO
 
VC-10
Posts: 3546
Joined: Tue Oct 26, 1999 11:34 am

RE: Bscu On Airbuses

Thu Mar 01, 2001 5:49 pm

Dc10Hound.

Steer-by-wire isn't rocket science. Put simply, a tranducer in the Tiller Assy transmits steering commands to a torque motor in the Metering Valve Assy. T/shooting isn't a problem, as it is a reliable system.

I could ask what is wrong with electrical signals Boeing ? Join us in the 21st Century.


 
Buzz
Posts: 694
Joined: Sun Nov 21, 1999 11:44 pm

A320 Steering

Fri Mar 02, 2001 3:02 am

Hi DC10hound, and A320FO, Buzz here. I tend to spend most nights of the week working on our A319/A320 fleet because i've taken the time to learn how to 'speak' Airbus.
The Brake/Steering system is pretty trouble-free, no real problems in the last 5 years.
There are 2 tillers for nosewheel steering, one for each pilot. If they start arguing, the deflections are added together. One night my Lead was demonstrating this on another mechanic, they were all over the taxiway, almost made tracks in the mud as they added/subtracted inputs to the tillers. Steer by wire? It works for us.
Only 1 nosewheel steering actuator, instead of 2. And the steering turns 95 degrees each side of the centerline.
If i was going to teach aircraft towing to somebody, i'd use a 'Bus. It's almost impossible to turn it past the NLG steering limits and you can see under the airplane so you know where the Main Gear tires are. And it's got a short wheelbase, so your steering inputs from the tug show up right away.
g'day
 
cricri
Posts: 540
Joined: Sat Oct 02, 1999 12:10 am

RE: Bscu On Airbuses

Sat Mar 03, 2001 9:13 am

Tx for your replies all !  Smile/happy/getting dizzy
 
dc10hound
Posts: 460
Joined: Fri Dec 15, 2000 4:18 pm

RE: Bscu On Airbuses

Mon Mar 05, 2001 2:59 am

OK, VC-10, my last post was overly sarcastic. This one might be so also  Big grin.

But in my humble opinion, almost everything Airbus does IS rockect science. Nothing that Douglas (a REAL aircraft company) or Boeing did was good enough for Airbus, they had to go ahead and re-invent aviation. Smokin cool

As you may be able to tell, I,m just throwing some "Bait" out there, and see who will bite...

Is there any good fishing where you are?
"A bad day fishing beats the heck out of a good day at work" -Anon

A320FO, thanks for the "input" (pardon the pun) , your answer was succinct, and what I sort of suspected.

Buzz, thx for your weigh in.

Cricri, as you can see, us aviation professionals can always violently agree.

Good day to all, and keep'em flyin' Big grin
-hound
"Eagles soar. But weasels never get sucked into jet intakes.."

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