767-300 brakes question
08-20-2015, 01:25 PM
#12
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Joined APC: Aug 2013
Posts: 2,159
Spoke to someone in MX and CPO. Sub UA 76's have steel brakes.
The conversion to carbon brakes was planned, budgeted for, and moneys allocated. At last minute plug was pulled and moneys diverted to something else. That's what I know anyways.
The conversion to carbon brakes was planned, budgeted for, and moneys allocated. At last minute plug was pulled and moneys diverted to something else. That's what I know anyways.
08-20-2015, 04:39 PM
#14
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Maybe they flew a DC-9 or MD-80 where the reversers can drastically hurt your steering ability on runways with less friction.
08-20-2015, 05:10 PM
#15
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I've seen quite a few Captains using flaps 25 with autobrakes lately. Granted, I haven't been on the plane for very long. I consistently use flaps 30 with brakes off because that's what I was taught in training. It doesn't affect the price of beer so I haven't given it any thought.
08-21-2015, 05:59 AM
#16
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Joined APC: Feb 2011
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767-300's have carbon brakes. They are very good brakes, but good for only 1 stop. Using auto brakes will actually elevate your brake temps over later manual braking, regardless of what TK says. Brake wear is different than brake temps.
If you want less brake wear, use auto brakes, but you will have higher temps, because it brakes earlier in the landing roll=more energy dissapated through braking.
If you want lower temps, don't use auto brakes, use more reverse, and longer roll with later light manual braking. Fewer number of applications and lighter manual braking will dramatically lower temps.
Hard to do both. If you do it the TK way and maximize the use of autobrakes, you will have higher temps.
If you want less brake wear, use auto brakes, but you will have higher temps, because it brakes earlier in the landing roll=more energy dissapated through braking.
If you want lower temps, don't use auto brakes, use more reverse, and longer roll with later light manual braking. Fewer number of applications and lighter manual braking will dramatically lower temps.
Hard to do both. If you do it the TK way and maximize the use of autobrakes, you will have higher temps.
08-21-2015, 06:30 AM
#17
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Joined APC: Feb 2008
Posts: 4,099
When DAL switched over to carbon brakes, we were told that the hotter carbon brakes become, the harder the actual carbon material becomes. Just like tempering steel. Less actual brake material is abraided away on the pads as temperature increases.
08-21-2015, 06:40 AM
#18
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KE being a squared function of velocity means ten knots absorbed at the beginning of the rollout could be ten times as much energy as ten knots at the end of the rollout.
I prefer Auto 1 or 2 until I get the nose on the pavement, then go manual. Exceptions: places like Maui with rain and Vtgt pushing 160 kts.
I was told way back on the 747-400 (when it was one of the few planes that had Carbon brakes) that it is the number of cycles that wears them out. They said Auto would hold a more consistent pressure. They said constant or increasing brake pressure was good, but every reduction is what caused the wear.
As an engineer, this makes sense to me. I wonder if a red-hot carbon brake, being "smothered" by its matching surface, would not burn-off a few millimeters of carbon every time the brake was released, and air---and oxygen---were to flow in.
08-21-2015, 06:40 AM
#19
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Joined APC: Jan 2011
Position: 737 Captain
Posts: 233
This is all true I watched a video put out by, I think Cleveland Brakes, that went into all the science behind this.
08-21-2015, 07:02 AM
#20
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Joined APC: Jun 2014
Posts: 303
I've seen quite a few Captains using flaps 25 with autobrakes lately. Granted, I haven't been on the plane for very long. I consistently use flaps 30 with brakes off because that's what I was taught in training. It doesn't affect the price of beer so I haven't given it any thought.
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