Brakes Use.ppt

Customer Services

Airbus recommendations for a proper operation of carbon brakes

by Guy Di Santo

Airbus recommendations for a proper operation of carbon brakes22

Contents

Protection against high brake temperature and fire

Carbon brakes life Preferred carbon braking techniques Optimizing brake temperature

Airbus recommendations

Conclusion




Regulation requirementsRegulation 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”



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 brake 400°C ensures an adequate margin with the auto ignition

temperature of all hydraulic fluids allowed to be used

The main purpose of the The main purpose of the BRAKE HOTBRAKE HOT warning is to prevent fire in the L/G bay in warning is to prevent fire in the L/G bay in

case of hydraulic leakage when L/G is case of hydraulic leakage when L/G is retractedretracted

Airbus design philosophyAirbus design philosophy

Fire protection is ensured by fire Fire protection is ensured by fire preventionprevention



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 Brake fans should be considered as part of the braking system when short turn around of the braking system when short turn around

times are requiredtimes are required

Airbus design philosophy Airbus design philosophy (cont’d)(cont’d)


Contents




Conclusion

Carbon brakes life


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 applicationsNumber of brake applications Brake temperatureBrake temperature


Carbon brake life: Preferred Braking Techniques

Reducing the number of brake applicationsReducing 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 temperatureOptimizing brake temperature Operate the brakes in temperature ranges where

carbon wear is minimum


Messier-Bugatti

Carbon brake life: Optimizing Brake Temperature

100 200 300 400 500 Disk temperatureC

080

Indicated temperatureC250 500

600

wear rate


Honeywell - ALS

180 405 630 Disk temperatureC

0150

Indicated temperatureC315 480

wear rate



Disk temperature (°C)0 100 200 300 400 500

80 165 250 335 420 500

600

Indicated temperature (°C)

Wear rate

Goodrich



Messier - Bugatti

Honeywell-ALS

Goodrich

Wear rate

80Indicated temperatureC

250150 315 5000



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


Brake temperature management during taxiBrake temperature management during taxi

Taxi in

Taxi out


Messier - Bugatti

Honeywell-ALS

GoodrichWear rate

Brake temperature management during taxiBrake temperature management during taxi

Brake hot Brake hot warningwarning

Taxi inTaxi inTaxi outTaxi out

80Indicated temperatureC

250150 315 5000




Brake manufacturers recommendations Taxi inTaxi in: keep the brakes hot

Taxi outTaxi 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 taxiBrake Temperature Management during taxi

Brake temperature management is not easy Up to 150°C difference between brakes in normal operation

A good tool: the brake cooling fans


Hot brakes: setting the limitsHot brakes: setting the limits

Taxi outTaxi out: Airbus does not promote any procedure that would intentionally increase brake temperature before takeoff Ensure max energy is sustained at RTO Ensure Brake Hot warning will 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 inLanding/Taxi in: Thermal oxidation accelerated at high temperature Brakes should not be repeatedly operated above 500°C Brake fans increase oxidation if brakes are not thermally

stabilized



Contents




Conclusion



Airbus Recommendations

Autobrake at landingAutobrake 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 takeoffAutobrake at takeoff

Use Max to improve safety



Engine thrust reversersEngine thrust reversers

For safety reasons, select full reverse thrust after main Landing Gear touches down If restricted by airport regulations, select idle reverse



Taxi out:Taxi out: Fans ON when temperature >100°C (arc on ECAM)

Before takeoff:Before takeoff: If temperature >150°C (fans ON), delay takeoff (except ABS) Fans OFF when temperature <150°C

Taxi in:Taxi in: Normal operation:

• Fans selection delayed for 5 minutes or at the gate Short turnaround or temperature likely to exceed 500°C

• Select fans (forget oxidation)

Parking:Parking: Fans OFF if temperature < 100°C (no arc on ECAM)

Brake cooling fans (if installed)Brake cooling fans (if installed)



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 brakeParking brake

Prolonged parking brake application on hot brakes can be detrimental to brakes (dragging, oxidation, …)



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 brakeParking brake

Do not pull parking brake in flight...Do not pull parking brake in flight...

…this does not help slow down the aircraft


Contents




ConclusionConclusion


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 views Some recommendations for carbon brake saving

should be customized

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Brakes Use.ppt