Airbus Recommendations for a Proper Operation of Carbon Brakes
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Transcript of Airbus Recommendations for a Proper Operation of Carbon Brakes
Customer Services
Airbus recommendations for a proper operation of carbon brakes
by Guy Di Santo
Airbus recommendations for a proper operation of carbon brakes2
Contents
Protection against high brake temperature and fire
Carbon brakes life Preferred carbon braking techniquesOptimizing brake temperature
Airbus recommendations
Conclusion
Protection against high brake temperature and fire
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 flammable fluids 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 relevant hazards if ignition does occur”
Airbus recommendations for a proper operation of carbon brakes4
Protection against high brake temperature and fire
A BRAKE HOT warning renders the probability of a fire of hydraulic origin extremely remote when L/G is retracted
The indicated temperature (e.g. 300°C) corresponds to about 400°C in the hottest part of the brake400°C ensures an adequate margin with the auto ignition temperature of all hydraulic fluids allowed to be used
The main purpose of the BRAKE HOT warning is 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 fire prevention
Airbus recommendations for a proper operation of carbon brakes5
Protection against high brake temperature and fire
Getting BRAKE HOT warning 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 the braking system when short turn around times are
required
Airbus design philosophy (cont’d)
Airbus recommendations for a proper operation of carbon brakes6
Contents
Protection against high brake temperature and fire
Carbon brakes life Preferred carbon braking techniquesOptimizing brake temperature
Airbus recommendations
Conclusion
Carbon brakes life
Airbus recommendations for a proper operation of carbon brakes7
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 applicationsBrake temperature
Airbus recommendations for a proper operation of carbon brakes8
Carbon brake life: Preferred Braking Techniques
Reducing the number of brake applicationsDo not ”ride” the brakes Single (two on A340) engine taxiAlternate left and right braking when taxiing slowlyUse of autobrake at landing
Optimizing brake temperatureOperate the brakes in temperature ranges where carbon wear is minimum
Airbus recommendations for a proper operation of carbon brakes9
Messier-Bugatti
Carbon brake life: Optimizing Brake Temperature
100 200 300 400 500Disk temperature ° C
080
Indicated temperature ° C250 500
600
wear rate
Airbus recommendations for a proper operation of carbon brakes10
Honeywell - ALS
180 405 630Disk temperature ° C
0150
Indicated temperature ° C315 480
wear rate
Carbon brake life: Optimizing Brake Temperature
Airbus recommendations for a proper operation of carbon brakes11
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
Airbus recommendations for a proper operation of carbon brakes12
Messier - Bugatti
Honeywell-ALS
Goodrich
Wear rate
80Indicated temperature ° C
250150 315 5000
Carbon brake life: Optimizing Brake Temperature
Airbus recommendations for a proper operation of carbon brakes13
00
Time (minutes)50 100 150 200 250 300 350 400
100
200
300
400
500
600
700
Tem
pera
ture
(°C
)
Taxi in
landingTaxi 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
Airbus recommendations for a proper operation of carbon brakes14
Messier - Bugatti
Honeywell-ALS
GoodrichWear rate
Brake temperature management during taxi
Brake hot warning
Taxi inTaxi out
80Indicated temperature ° C
250150 315 5000
Carbon brake life: Optimizing Brake Temperature
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 80°C”Honeywell-ALS: “below 150°C”Goodrich: “warm or hot”ABS: “optimum indicated temperature is 150°C”
Brake Temperature Management during taxi
Brake temperature management is not easyUp to 150°C difference between brakes in normal operation
A good tool: the brake cooling fans
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Hot brakes: setting the limits
Taxi out: Airbus does not promote any procedure that would intentionally increase brake temperature before takeoff
Ensure max energy is sustained at RTOEnsure Brake Hot warning will not appear just prior to takeoffIf 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 500°CBrake fans increase oxidation if brakes are not thermally stabilized
Carbon brake life: Optimizing Brake Temperature
Airbus recommendations for a proper operation of carbon brakes17
Contents
Protection against high brake temperature and fire
Carbon brakes life Preferred carbon braking techniquesOptimizing brake temperature
Airbus recommendations
Conclusion
Airbus recommendations
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 MEDOn 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
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
Airbus recommendations for a proper operation of carbon brakes20
Airbus Recommendations
Taxi out:Fans ON when temperature >100°C (arc on ECAM)
Before takeoff:If temperature >150°C (fans ON), delay takeoff (except ABS)Fans OFF when temperature <150°C
Taxi in:Normal operation:
• Fans selection delayed for 5 minutes or at the gateShort turnaround or temperature likely to exceed 500°C
• Select fans (forget oxidation)
Parking:Fans OFF if temperature < 100°C (no arc on ECAM)
Brake cooling fans (if installed)
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Airbus Recommendations
Brake temperature > 300°C (150°C fans ON)Release parking brake at the gate after chocks are in place
Brake temperature > 500°C (350°C fans ON)Avoid parking brake application, unless operationally necessary
Parking brake
Prolonged parking brake application on hot brakes can be detrimental to brakes (dragging, oxidation, …)
Airbus recommendations for a proper operation of carbon brakes22
Airbus Recommendations
Some cases have been reported where the parking brake 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
Airbus recommendations for a proper operation of carbon brakes23
Contents
Protection against high brake temperature and fire
Carbon brakes life Preferred carbon braking techniquesOptimizing brake temperature
Airbus recommendations
ConclusionConclusion
Airbus recommendations for a proper operation of carbon brakes24
Conclusion
Braking system design philosophy is based on fire prevention
Airbus takes into account in-service experience and brake manufacturers’ data for providing best operating procedures
Brake manufacturers do not have all the same viewsSome recommendations for carbon brake saving should be customized