cmckeithen
Posts: 594
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Autobrake System On A/C

Sat Mar 06, 2004 6:29 am

Which is the best Autobreaking to use and what do each do?

Auto Break 1
Auto Break 2
Auto Break 3
Auto Break 4
Max Auto Break
 
Critter_592
Posts: 269
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Autobrake System On A/C

Sat Mar 06, 2004 6:45 am

1 is less aggressive than 4 or Max. Max is normally used in an emergency or extremely wet/icy conditions. I think the average is 2, maybe 3 depending on the runway length.
 
3204ever
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Autobrake System On A/C

Sat Mar 06, 2004 7:59 am


Max breaking,short run way...
 
OPNLguy
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Autobrake System On A/C

Sat Mar 06, 2004 8:13 am

I believe that's "autobraking"....

"Autobreaking" is when the aircraft keeps going out of service for successive technical faults...  Big grin
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
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Starlionblue
Posts: 17117
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Autobrake System On A/C

Sat Mar 06, 2004 8:15 am

... and hot brakes, and more wear, and scared passengers, which is why there are several levels. Normally, you would want to use as little as you need to get you to the right turnoff.

And may I say that spelling it "autobrEaking" cracks me up. "Press the autobreak, we'll roll halfway down the runway, then split in three large burning pieces."
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
OPNLguy
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Autobrake System On A/C

Sat Mar 06, 2004 8:20 am

>>>And may I say that spelling it "autobrEaking" cracks me up

We commonly see the same thing each winter when we get "breaking action reports" from some stations. If the "breaking" action is reported, I guess it means that the "braking" action isn't very good, and there's one off the end somewhere in pieces...  Big grin
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
VC745D
Posts: 208
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Autobrake System On A/C

Sat Mar 06, 2004 8:44 am

did the Spell Check button brake?
 
cmckeithen
Posts: 594
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Autobrake System On A/C

Sat Mar 06, 2004 8:47 am

Yes the spell button broke. Sorry for not being perfect, but if it will make you happy, I will fix it.
 
OPNLguy
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Autobrake System On A/C

Sat Mar 06, 2004 9:46 am

>>>Sorry for not being perfect,

Believe me, you're not the first person to confuse break/brake, and you certainly won't be the last. I don't think anyone was trying to imply that you weren't perfect (and NOBODY is), but were just trying to see that there is a difference. Were you to use "break" instead of "brake" during some point in an aviation career, someone higher up in the food chain might conclude that you were "unclear on the concept" or something. You'd rather know -now-, from freinds here on A.net, right?

Cheers...
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
cmckeithen
Posts: 594
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Autobrake System On A/C

Sat Mar 06, 2004 11:35 am

Yes....thanks for the advice and correction. I was not trying to be harsh if I sounded like it. And if I was a smartass I am sorry for being that way.

Chris
 
OPNLguy
Posts: 11191
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Autobrake System On A/C

Sat Mar 06, 2004 3:25 pm

>>>Yes....thanks for the advice and correction.

No prob...  Big grin
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
Guest

Autobrake System On A/C

Sat Mar 06, 2004 8:21 pm

Autobrake 1-2-3-4-MAX on modern airplanes, and...
Autobrake MIN-MED-MAX on my dinosaur 747-200s or 300s select a "rate" of deceleration by applying brakes. In both cases of MAX - 3,000 psi of hydraulic pressure is sent to the brakes for stopping the airplane, i.e. in emergency.
xxx
What is another fact is when selecting MIN (or A/B-1), with little deceleration required, if you use "full reversers" for that landing, chances are that the brakes will not even be applied, until... you get "out" of using reversers.
xxx
Happy contrails  Smile
(s) Skipper
 
AA717driver
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Autobrake System On A/C

Sun Mar 07, 2004 1:40 am

It's ok to be a smartass on this board. It's not ok to be sensitive.  Big grin

On the 757, the only place I ever used autobrakes was SNA. Even then, it wasn't necessary. Usually, the natural tendency was to get on the brakes at 100 kts.(which disables autobraking) anyway.

I've been told that Max. gives the effect of an arrested landing! Then you have to wait to be dragged off the runway when the fuse plugs go off... Big grin TC
FL450, M.85
 
Rick767
Posts: 2613
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Autobrake System On A/C

Sun Mar 07, 2004 1:55 am

Remember on several aircraft, like the 757/767, MAX autobrake provides less retardation than full manual braking.
I used to love the smell of Jet-A in the morning...
 
BMAbound
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RE: Autobrake System On A/C

Sun Mar 07, 2004 2:16 am

Critter_592,

I was just wondering, is 4 or MAX really used for wet/icy conditions? To me, the chances of hydroplaning/skidding off the runway seem to increase if pilots are braking hard right after touchdown on a rainy day.

johan

Altitude is Insurance - Get Insured
 
3204ever
Posts: 21
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RE: Autobreaking System On A/C

Sun Mar 07, 2004 2:22 am



On the Airbus 320 there is 3 modes.

MAX mode is normally selected for take off.

MED or LO modes may be selected for landing.

When LO is selected,progressive pressure is sent to the brakes 8 seconds after the ground spoiler deployment order to provide a 1.7 m/s deceleration.

When MED is selected,progressive presure is sent to the brakes immediatly after the ground spoiler deployment order to provide a 3 m/s deceleration.
 
Mr.BA
Posts: 3310
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RE: Autobrake System On A/C

Thu Mar 18, 2004 5:45 pm

Just a side note, MAX setting is not allowed to be used for landing. Should harder braking be needed than MED, pilots brake manually.
Boeing747 万岁!
 
rendezvous
Posts: 531
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RE: Autobrake System On A/C

Fri Mar 19, 2004 6:06 am

Some planes also have the "RTO" setting don't they? I assume that means if you pull the power off during takeoff roll the planes stops real quick?
 
Guest

RE: Autobrake System On A/C

Fri Mar 19, 2004 6:20 am

RTO position - Rejected Take-Off...
xxx
When armed, with RTO ON, if you slam your throttles closed, you get MAX brakes...
Spoilers deploy also at the same time... while you get busy getting these reversers...
xxx
Happy contrails  Smile
(s) Skipper
 
Mr.BA
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RE: Autobrake System On A/C

Fri Mar 19, 2004 8:19 am

Hi Skipper,

I'm not sure about this but I think there is a certain 'speed limit' before the RTO brakes goes into action?

Let's say you abrt at 50 knots, would it come on? Or would it only come on above 70 knots? What about the spoilers?

Thanks!
Boeing747 万岁!
 
Mr Spaceman
Posts: 2723
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RE: Autobrake System On A/C

Fri Mar 19, 2004 8:30 am

Hi guys.

I've never seen any type of airliner rolling out after landing with smoke rising from some of the brakes, as can be seen in this photo, so I don't believe this BA 747's brakes are experiencing a normal situation.

What do you guys think would have caused these brakes to smoke like this? High pressure braking action or a mechanical problem?

Perhaps a set of brakes got locked up for some reason. Whatever the cause, I wonder if these brakes would cause a delayed turn-around so they had time to cool off?


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Photo © Joe Pries - A.T. TEAM



PS, I don't think this smoke is from the 747's initial touchdown ......... thus the questions. Big grin


Chris  Smile


"Just a minute while I re-invent myself"
 
AJ
Posts: 2295
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RE: Autobrake System On A/C

Fri Mar 19, 2004 8:39 am

Alvin, on the 767 the RTO function of the autobrakes is activated passing 85kt groundspeed.

Chris, recently serviced brakes can smoke like that if excess grease/dust similar remains in the brake area.

Carbon brakes thrive in the heat, so the high temperatures can cause foreign materials to burn off after application. This is generally a short lived phenomenon. There is a limit of course, get the brakes too hot and you can wind up blowing the fuse plugs on your tires...embarassing and dangerous! It also increases the downtime of the aircraft having hot brakes, as they must have cooled sufficiently to allow the RTO function to effectively operate on the next takeoff. Fans are sometimes used during short turnarounds to help cool hot brakes.

Cheers.
 
Mr.BA
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RE: Autobrake System On A/C

Fri Mar 19, 2004 9:45 am

Thanks AJ. Just wondering, what is the minimum brake temperature before the RTO is being allowed to function on the next takeoff? Or do the B767s read the brake temperature in units?
Boeing747 万岁!
 
AJ
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RE: Autobrake System On A/C

Fri Mar 19, 2004 10:07 am

Yes, the brake temperatures are displayed in values from 0 to 9. A Brake Temp light illuminates for values of 5 or above. Releasing the parking brake (on chocks of course) can help reduce brake temperatures.

If the Brake Temp light comes on for the next takeoff a table entitled 'Max Quick Turnaround Limits' is consulted. A minimum turnaround time of 75 minutes must be applied (would cause chaos on a Cityfler!).

The table limits the takeoff weight for the next flight. For example after a Flap 30 landing at Sydney on a 20 degree day the next takeoff weight with hot brakes is limited to 149,000kg.
 
Mr.BA
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RE: Autobrake System On A/C

Fri Mar 19, 2004 1:08 pm

Thanks AJ for the imput. I don't know if many airlines do this... would it be viable to use more reversers (definately more than idle) during hot days and fast turnaround time? I guess that would ease a lot of pressure on the brakes upon rollout?

I note that cost-saving carriers like Swiss always use full reversers for landings. I don't think it saves more money than using more brakes?

Cheers!
Boeing747 万岁!
 
Guest

RE: Autobrake System On A/C

Fri Mar 19, 2004 7:53 pm

The RTO gets automatically armed at 80 Kts during takeoff for a 747.
xxx
As far as brake temperature gages... we have gages with green, yellow and red. To start a takeoff, all 16 temperatures must be in the "green" to insure the brakes to be capable of perform in case of a rejected takeoff.
xxx
We sometimes also monitor the brake temperature after gear retraction, if any temperature gage shows red, we re-extend the gear after takeoff, as soon as we are clear of climb obstacles, and leave the gear down for cooling two or three minutes. Boeings have "wheel well" fire warning detection, as well, had that a few times, because of overheated brakes (or long taxi).
xxx
In the old days, we had to do touch-and-goes for pilot training in the actual aircraft. We could not do it in simulators. So, after a few landings/takeoffs, we would leave the gear down occasionally, for cooling.
xxx
As AJ mentioned, all Boeings have "minimum turnaround charts"... we do not deal much with that in the 747s. We also have brake cooling temperature charts, where you enter speed at which brake were applied, weight of the aircraft... etc. and you end up when a "cool off" time.
xxx
Chris - brakes smoking -
That happens when the brakes are "brand new" and never were used. It is often seen on airplanes (or separate brakes) after maintenance changes brakes. Expect to see some smoke on the first landing for "new brakes"...
xxx
Happy contrails  Smile
(s) Skipper
 
CX Flyboy
Posts: 6039
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RE: Autobrake System On A/C

Fri Mar 19, 2004 9:55 pm

On the 777, we use Autobrake 2, 3 and sometimes 4 for a short runway like Fukuoka or Nagoya when wet. For long runways we used to use Autobrake 1, but the slow gentle application by the brakes wears down the brakes more and also leaves them quite hot. If landing on a long runway and rolling towards the end, we are advised to use Autobrakes 2, and release them at around 100kts and coast down to the end, using manual braking to slow down approaching our exit.
 
Mr Spaceman
Posts: 2723
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RE: Autobrake System On A/C

Sat Mar 20, 2004 5:37 am

Hi guys.

> AJ & B747skipper, Thanks for explaining that seeing smoke from the brakes is normal after maintenance has serviced the brakes or installed new ones.

Here's a question regarding warning lights and Auto Brakes.

On Thursday, March 11, 2004, a FedEx A300 (N682FE) had a failure of all eight main landing gear tires during it's landing roll at Fort Lauderdale Intl Airport (FLL) in Florida. There was smoke & fire coming off the MLG and the crew evacuated the A300 out the right forward door slide.

The captain was asked by company maintenance personnel to perform an "Alternate Brake In-Flight Test" which she complied with while at the top of her climb.

She reported on the FedEx form M-0627B 3/00 ..........

"Good pressure left shows 2100, right shows 2500, however we get a brake fail light and ECAM amber alert 'Auto BRK fault'."

After the test she returned the switch to the "normal".

Here's the NTSB report.

http://www.ntsb.gov/ntsb/brief.asp?ev_id=20040315X00323&key=1

My questions are ....... What is done during the Alternate Brake In-Flight Test?

Also, what does "ECAM" stand for?

Finally, would an amber alert for an Auto BRK Fault cause the crew to be aware that the Auto Brakes might apply themselves apon landing even though they're not selected, based on training? Or do you think they where completely surprised?

Here's the FedEx A300 involved, while taxing at FLL.


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Photo © Mark Kopczak



Thanks,

Chris  Smile
"Just a minute while I re-invent myself"
 
3204ever
Posts: 21
Joined: Sat Mar 06, 2004 12:58 am

RE: Autobrake System On A/C

Sat Mar 20, 2004 6:14 am



ECAM=Electronic Centralized Aircraft Monitoring..
 
Mr Spaceman
Posts: 2723
Joined: Thu Mar 15, 2001 5:09 am

RE: Autobrake System On A/C

Sat Mar 20, 2004 7:21 am

Hello 3204ever.

Thanks for your answer about what ECAM stands for. Big grin

I guess the in-flight test is pretty simple. The Captain probably just looks at some gauges that show what the hydraulic pressure is at for the brakes on the main gear.

I am wondering what the word "Alternate Brake" means though? Perhaps it's just a different hydraulic source that's used for backup incase the normal source for the brakes has a leak or something.


Chris  Smile
"Just a minute while I re-invent myself"
 
liamksa
Posts: 301
Joined: Mon Oct 29, 2001 1:13 pm

RE: Autobrake System On A/C

Sat Mar 20, 2004 9:09 am

Gday Mr Spaceman

Don't know the specifics of the A300, but i'd imagine it would be similar to other modern aircraft. In the case of the B767, the normal source of brake pressure is the right hydraulic system. In the event of a failure, the alternate system is used (centre hydraulic system for B767).

In the unlikely event both systems fail there is a third source of pressure - the hydraulic accumulator (which can be thought of as a store of hydraulic pressure if you like). This will provide sufficient pressure for several brake applications.

In the photo below (i know you like photos  Smile ) you can see the brake pressure gauge (indicating ~ 2100 psi), which will indicate system pressure when the hydraulics are powered, or accumulator pressure when they aren't.

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Photo © Mariusz Siecinski



Cheers

Rob.
 
3204ever
Posts: 21
Joined: Sat Mar 06, 2004 12:58 am

RE: Autobrake System On A/C

Sat Mar 20, 2004 9:20 am

On the Aibus 320 series,there are 4 braking modes available depending on:

-The hydraulic system in use.
-The position of the A/SKID NOSE WHEEL switch and PARKING BRK control
switch.

NORMAL BRAKING:

The normal braking mode is supplied by the green hydraulic system.

ALTERNATE BRAKING WITH ANTI SKID:

The alternate braking mode is supplide by the yellow hydraulic system,
this mode is obtained if the green hydraulic pressure is insufficient or in event of failures on the normal system.

ALTERNATE BRAKING WITHOUT ANTI SKID:

Normally due to electrical supply failure.

PARKING BRAKE:

Hydraulic pressure is supplied from the yellow system or from the brake accumulator..



3204ever...





 
Mr Spaceman
Posts: 2723
Joined: Thu Mar 15, 2001 5:09 am

RE: Autobrake System On A/C

Mon Mar 22, 2004 6:52 am

Hi guys.

>> Liamksa, Thanks for your information and for providing that 767 photo. Big grin

Here's the best shot I could find of an A300's cockpit that shows what I suspect is the brake pressure gauge. It's on the center panel above the left side LCD display.

It has 3 needles on it. I guess one's for the left & right sides, and the third needle (on the top) is for alternate pressure perhaps. Unfortunately the photo's not clear enough to read the words.


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Photo © Jos Schoofs



Chris  Smile
"Just a minute while I re-invent myself"

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