airbus, triple-brakepressure-ind

[hetfield]

What would be your course of action if you observe the RH and LH triple-brakepressure-ind showing 1.000 psi or so during normal braking?

[Dream Land]

Stop and request a tow back to the stand? :confused:

[hetfield]

Wow!

That's fast and exactly what we did, albeit it wasn't a tow back. More a tow fwd after landing.:O

[Cardinal]

I assume you experimented with the "Press Harder" solution?

[Bolty McBolt]

Were you on auto brakes or feet on the pedals ??

If your feet were on the pedals I suspect you may have been on alternate brake system.
But more info needed..:ok: and I will do some reading

A330 or A320???

[Dream Land]

Hadn't seen this problem yet, when you find out what was wrong let us know. :8

[hetfield]

Were you on auto brakes or feet on the pedals ??

No auto brake, man at work:O.

Yes the alternate braking system was in charge than.

[Back Seat Driver]

I am trying to resist the temptation on asking about the position of the Anti-Skid/Nosewheel steering switch.

[hetfield]

I am trying to resist the temptation on asking about the position of the Anti-Skid/Nosewheel steering switch.

Why?

Go ahead:O

[tubby linton]

Normal braking in the A300 is electrically signaled.Alternative brakes is manual.You would have been in alternative brakes with anti-skid with the brake selector in normal/on.Hence you get an indication on the triple indicator.
I have seen braking only on one side with an A300,due to the brake master valve failing.Not nice on a short runway!

[guiones]

A320 series answer:

Under normal circumstances, with the engines running, normal braking comes from the green hydraulic system. If you have the engines running and positive pressure on the triple indicator with the foot brakes, then the alternate braking system (yellow) or accumulator pressure is showing. That is why you have the break test after engine start. The only other way to have positive pressure on the triple indicator with engines running is to set the parking brake(yellow).

G

[hetfield]

during normal braking?

I have to correct myself. Assuming normal braking, e.g. all switches normal, no hydraulic failure.

[Conan The Barber]

Why would you want to be towed to stand if you are on alternate brakes?

[145qrh]

What about BSCU reset,ie turning A/SKID NWS off then on...?

Not sure about 320, think its almost same as 330/40.

[FlightDetent]

What about BSCU reset,ie turning A/SKID NWS off then on...? Not sure about 320, think its almost same as 330/40. Careful! No rush on the switch. See Ali in Naples. There is bloody more to brakes than A/NWS. Unpublished memory items resets? No thanks.

hetfield: On landing roll and deccelerating normally, may we suppose? Keep the psi below 1000. Keep heart bpm below 180 when approaching the terminal. Do not shut down the HYD (via Y elec + ptu as necessary) until positively chocked-in, belt and braces, really. Do not attempt to troubleshoot any more than needed on the wire-bus. Make a nice TLog entry with a black pen and walk safely home while the experts on duty take over and work their magic. My desktop decision.

You have feedback of what actually happened? Crosslinked channels fed into the TPI?

FD (the un-real)

[Conan The Barber]

It's a bit meaningless to answer the question as Hetfield, for some reason, hasn't said what type of Airbus he is talking about. It could be anything from A300 to A380.

A rather maladroit way of asking a question. If you want an answer that is.

[Hardass56]

He's being an academic siit!:rolleyes:

[Uber05]

Hetfield, was the aircraft braking normally - even after it self switched to alternate ( as the triple indicator was showing ) ? Did you notice on lower ecam display the green coloured Altn Brk legend ?

[tubby linton]

The parking brake is electrically controlled.The A300,which I believe Hetfield is referring to,has a parking brake lever that pulls out and then turns to secure it in place.Even partially pulled out can lead to parking brake on.This leads to all other braking being disconnected!!!This may not be obvious to the crew until loss of braking is evident.
The braking system is not one of the better systems on airbus aircraft!

[hetfield]

Yes tubby linton is correct.Even partially pulled out can lead to parking brake on.This leads to all other braking being disconnected!!!This may not be obvious to the crew until loss of braking is evident.
The braking system is not one of the better systems on airbus aircraft!Why would you want to be towed to stand if you are on alternate brakes?Cause we didn't know what actually happened. HYD normal no warnings etc.

@dreamland

Can't realy tell what the problem was cause many parts have been changed thereafter e.g. automatic selector valve, BSCU, parking brake mechanism(!!!)

[Bolty McBolt]

Hetfeild

Any chance you could give the airbus type so a manual or notes can be consulted to give you an answer.

Seeing pressure on the triple indicator means for some reason the alternate brake system was doing the braking. Not the primary.
At the time I may have suggested bring the aircraft to a stop parking the brakes and selecting the Antiskid/ NWS off then on(cycling the BSCU) probably would have been a useful thing to do from a trouble shooting stand point and may have solved the problem. Being towed back to blox seems extreme but I was not there, So now its history..

[hetfield]

@Bolty

A300 but afaik not much different to 320/340 beside the twisted yellow/blue hyd-system.

[tubby linton]

Bolty,The triple indicator also shows parking brake pressure !

[Bolty McBolt]

The triple indicator also shows parking brake pressure !

and parking brake system would be the alternate braking system...

[Conan The Barber]

Hetfield,

I would suggest that you did know what happened. The Normal brakes had failed.

As indicated there were no other indications to suggest any further failures. In fact, from you account, the Alternate brakes system was fully functional.

Alternate brakes is not a lesser system and is as effective as Normal brakes.

[Jetjock330]

If this was a A345/6 (http://64.233.183.104/search?q=cache:s2Vg60yN0PUJ:www.andytracy.net/32LG.doc+ebcu+airbus+alternate+brake&hl=en&ct=clnk&cd=1), at the gate, the alternate braking is controlled by the EBCU which regulates the pressure to 1000psi, which is normal to see.

Alternate braking is active when GRN pressure is insufficient provided that BLU pressure is available, A/SKID & N/W STRG switch is on and parking brake is not on. Auto switching from GRN to BLU systems is provided. BLU pressure indication to both left and right brake and accumulator pressure is provided. Autobrake is inop, A/SKID is operative. Alternate braking without A/SKID should not exceed 1000 PSI on the triple indicator. A346 pressure is auto-limited to 1000psi. A Nov 2000 telex from AI seeks to highlight the different "feel" of the braking system with the BRAKES ANTI-SKID FAULT ECAM message: basically with this message there is no anti-skid available and braking is only through the alternate braking system. When braking is applied on the alternate braking system the brake response is higher than on the normal braking system. This is particularly marked for small brake pedal deflections. Pure accumulator operation provides seven full brake applications. The parking brake is supplied by BLU pressure and is only on when it's ON! The BLU electrical pump may be used. Activation of the Parking Brake deactivates ALL other braking modes.



A343 is different.

[hetfield]

@Conan the Barber
The Normal brakes had failed.Yes obviously, but what part failed? Green Sys normal!?

I'm afraid I'm not the top bunk who knows everything about the complex systems behind AB.