brakes use
TRANSCRIPT
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Customer Services
Airbus recommendations for a proper
operation of carbon brakes
by Guy Di Santo
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Airbus recommendations for a proper operation of carbon brakes2
Contents
Protection against high brake temperature and fire
Carbon brakes life
Preferred carbon braking techniques
Optimizing brake temperature
Airbus recommendations
Conclusion
Protection against high brake temperature and fire
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Airbus recommendations for a proper operation of carbon brakes3
Protection against high brake temperature and fire
Regulation requirements
Flammable fluid protection:
in each area where flammablefluids or vapours might escape by
leakage of a fluid system, there
must be means to minimize the
probability of ignition of the fluids
and vapours, and the relevanthazards if ignition does occur
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Airbus recommendations for a proper operation of carbon brakes4
Protection against high brake temperature and fire
A BRAKE HOTwarning renders the probability of a fire of
hydraulic origin extremely remote when L/G is retracted
The indicated temperature (e.g. 300C) corresponds to about 400C
in the hottest part of the brake
400C ensures an adequate margin with the auto ignitiontemperature of all hydraulic fluids allowed to be used
The main purpose of the BRAKE HOTwarningis to prevent fire in the L/G bay in case of hydraulic
leakage when L/G is retracted
Airbus design philosophy
Fire protection is ensured by fireprevention
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Airbus recommendations for a proper operation of carbon brakes5
Protection against high brake temperature and fire
Getting BRAKE HOTwarning after landing is not an abnormal
situation
The warning is prone to reappear during taxi out if brakes have
not been cooled down enough
Brake fans should be considered as part of thebraking system when short turn around times are
required
Airbus design philosophy (contd)
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Airbus recommendations for a proper operation of carbon brakes6
Contents
Protection against high brake temperature and fire
Carbon brakes life
Preferred carbon braking techniques
Optimizing brake temperature
Airbus recommendations
Conclusion
Carbon brakes life
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Carbon brake life
Carbon brake wear is a very complex physical process
Tests and in-service experience identified two major
parameters affecting carbon brake life
Number of brake applications
Brake temperature
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Carbon brake life: Preferred Braking Techniques
Reducing the number of brake applications Do not ride the brakes
Single (two on A340) engine taxi
Alternate left and right braking when taxiing slowly
Use of autobrake at landing
Optimizing brake temperature
Operate the brakes in temperature ranges where
carbon wear is minimum
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Messier-Bugatti
Carbon brake life: Optimizing Brake Temperature
100 200 300 400 500
Disk temperature C
0
80Indicated temperature C
250 500
600
wear
rate
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Honeywell - ALS
180 405 630
Disk temperature C
0
150Indicated temperature C
315 480
wear
rate
Carbon brake life: Optimizing Brake Temperature
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Disk temperature (C)0 100 200 300 400 500
80 165 250 335 420 500
600
Indicated temperature (C)
Wear
rate
Goodrich
Carbon brake life: Optimizing Brake Temperature
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Messier - Bugatti
Honeywell-ALS
Goodrich
Wearrate
80Indicated temperature C
250150 315 5000
Carbon brake life: Optimizing Brake Temperature
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0
0
Time (minutes)
50 100 150 200 250 300 350 400
100
200
300
400
500
600
700
Temperature(C)
Taxi in
landing
Taxi out
parking
Indicated
temperature
Disk
temperature
1st flight 2nd flight 3rd flight
Carbon brake life: Optimizing Brake Temperature
Brake temperature management during taxi
Taxi in
Taxi out
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Messier - Bugatti
Honeywell-ALS
Goodrich
Wear
rate
Brake temperature management during taxi
Brake hot
warning
Taxi inTaxi out
80Indicated temperature C
250150 315 5000
Carbon brake life: Optimizing Brake Temperature
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Airbus recommendations for a proper operation of carbon brakes15
Carbon brake life: Optimizing Brake Temperature
Brake manufacturers recommendations
Taxi in: keep the brakes hot
Taxi out:
Messier-Bugatti: below 80C Honeywell-ALS: below 150C
Goodrich: warm or hot
ABS: optimum indicated temperature is 150C
Brake Temperature Management during taxi
Brake temperature management is not easy Up to 150C difference between brakes in normal operation
A good tool: the brake cooling fans
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Airbus recommendations for a proper operation of carbon brakes16
Hot brakes: setting the limits
Taxi out: Airbus does not promote any procedure that would
intentionally increase brake temperature before takeoff
Ensure max energyis sustained at RTO
Ensure Brake Hot warningwill not appear just prior to takeoff
If no brake fans, on short turnaround, taxi out with hot brakes is
acceptable (Brake Hot warning extinguished at the gate)
Landing/Taxi in: Thermal oxidation accelerated at high
temperature
Brakes should not be repeatedly operated above 500C
Brake fans increase oxidationif brakes are not thermally
stabilized
Carbon brake life: Optimizing Brake Temperature
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Airbus recommendations for a proper operation of carbon brakes17
Contents
Protection against high brake temperature and fire Carbon brakes life
Preferred carbon braking techniques
Optimizing brake temperature
Airbus recommendations
Conclusion
Airbus recommendations
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Airbus recommendations for a proper operation of carbon brakes18
Airbus Recommendations
Autobrake at landing
Recommended when need of brake application is
foreseen
On short or evenly contaminated runways: LO or MED
On long and dry runways: LO
Reduces the number of brake applications to one
Increases brake temperature to adequate values for taxi in
Autobrake at takeoff
Use Max to improve safety
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Airbus recommendations for a proper operation of carbon brakes19
Airbus Recommendations
Engine thrust reversers
For safety reasons, select full reverse thrust after main
Landing Gear touches down
If restricted by airport regulations, select idle reverse
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Airbus recommendations for a proper operation of carbon brakes20
Airbus Recommendations
Taxi out: Fans ON when temperature >100C (arc on ECAM)
Before takeoff:
If temperature >150C (fans ON), delay takeoff (except ABS)
Fans OFF when temperature
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Airbus recommendations for a proper operation of carbon brakes21
Airbus Recommendations
Brake temperature > 300C (150C fans ON)
Release parking brake at the gate after chocks are in place
Brake temperature > 500C (350C fans ON)
Avoid parking brake application, unless operationally
necessary
Parking brake
Prolonged parking brake application on hot brakes can bedetrimental to brakes (dragging, oxidation, )
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Airbus recommendations for a proper operation of carbon brakes22
Airbus Recommendations
Some cases have been reported where the parkingbrake has been selected in flight.
Due to a probable freezing of the parking brake selector
valve, it could be released in descent only
Parking brake
Do not pull parking brake in flight...
this does not help slow down the aircraft
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Airbus recommendations for a proper operation of carbon brakes23
Contents
Protection against high brake temperature and fire
Carbon brakes life
Preferred carbon braking techniques
Optimizing brake temperature
Airbus recommendations
Conclusion Conclusion
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Airbus recommendations for a proper operation of carbon brakes24
Conclusion
Braking system design philosophy is based on fireprevention
Airbus takes into account in-service experience and
brake manufacturers data for providing bestoperating procedures
Brake manufacturers do not have all the same views
Some recommendations for carbon brake saving
should be customized