14 th Performance & Operations Conference Bangkok, 4-8 April 2005 One/two engine taxi Review of associated recommendations Presented by: Michel DOCUS Group

14th Performance & Operations Conference Bangkok, 4-8 April 2005

One/two engine taxi Review of associated recommendations

Presented by:

Michel DOCUSGroup Manager A320 Family Operational Standards

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One/two engine taxi 2 14th Performance & Operations Conference Bangkok, 4-8 April 2005

Contents

Introduction

Why should I perform an “engine out” taxi ?

Conditions to perform an “engine out” taxi

F.A.Q. :

Do I need APU ?

Can I perform an “engine out” taxi in icing conditions ?

Can I brake during engine start/shutdown on S.A. ?

Can I perform the flight control check ?

Conclusion

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Introduction

Taxi time increases due to : Airport congestion

Increased airport size

Airport regulations

One Engine Out allowed on Single Aisle and A330

Two Engine Out allowed on A340

Engine out taxi already covered in FCOM 3.04.90 and “Getting to

grips with fuel economy” brochure

Increased use of one or two engine out taxi

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Contents

Introduction

Why should I perform an “engine out” taxi ?Why should I perform an “engine out” taxi ?


F.A.Q. :

Do I need APU ?




Conclusion

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Benefits of engine out taxi

Reduce CO2 emission (Kyoto protocol)

Save fuel

Save brakes

Reduce turn around time

Airport regulations

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Reduce CO2 emission

Kyoto protocol valid since 16 feb 2005

– Reduce CO2 emission to 1990’ level

– 1 ton of burnt fuel = 3.15 tons of CO2

Today no specific regulation edicted by ICAO

Future tax on airplane fuel ???

– Could be part of the measures taken by ICAO

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Fuel economy :

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Fuel economy per aircraft :

Single Aisle :

– average of 4.5 cycles/day

– 180kg per day : 65700 kg / year / aircraft65700 kg / year / aircraft

Long Range :– average 2.5 cycles/day

– 250kg per day : 91250 kg / year / aircraft91250 kg / year / aircraft

Results based on 8 minutes with engine outResults based on 8 minutes with engine out

Taxi on some airports may reached 45 minutes !!!Taxi on some airports may reached 45 minutes !!!

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Brakes saving

Lower thrust

Lower taxi speed

Reduced number of brake application

Brake saving

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Reduced turn around time

Reduced brake temperature

Prevent “Brakes Hot” warning

Less takeoff delays

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Airport regulations

To enhance safety but shutting down the engine near the air bridge

To reduce Noise– ”Getting to Grips with Aircraft Noise” brochure

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Contents

Introduction


Conditions to perform an “engine out” taxi Conditions to perform an “engine out” taxi

F.A.Q. :

Do I need APU ?




Conclusion

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Airbus recommendations before applying engine out taxi

Not recommended at high gross weight or uphill slope

High thrust increases Foreign Object ingestion risk

– Engine damage

Slow or tight taxi turn more difficult at high gross weight

Not recommended on slippery taxiways

More difficult to steer with asymmetric thrust

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Airbus recommendations before applying engine out taxi

Respect of the engine stabilization times

Minimum of 2 min engine warm up and 3 min cooldown time

To thermally stabilize the engine hot sections

In case of mechanical event,return to the gate may be required for maintenance action

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Contents

Introduction


When should I perform an “engine out” taxi ?

F.A.Q. :F.A.Q. :

Do I need APU ?Do I need APU ?




Conclusion

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F.A.Q.

Do i need APU to taxi with engine out ?APU use considered in the engine out taxi :

– APU use part of the SOP

– Minimize electrical transients

– Prevent smells/fumes entering the air conditioning during taxi in Start APU before arriving at the gate and before engine

shutdown

Minimizing APU use helps save fuel and reduces maintenance

– APU max consumption : between 125 (SA) and 290 kg/hr (A3456)

But APU is not necessary for engine out taxi

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Contents

Introduction


When should I perform an “engine out” taxi ?

F.A.Q. :

Do I need APU ?

Can I perform an “engine out” taxi in Can I perform an “engine out” taxi in icing conditions ?icing conditions ?



Conclusion

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F.A.Q.

Can I perform engine out taxi in icing conditions ?

FCOM / AFM :

Engine anti ice must be on

when icing conditions exist

or are anticipated:

– To avoid ice accretion on

nacelle and fan

Engine anti ice operative only on a running engine

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F.A.Q.

In icing conditions,non running engine will not necessarily ice :

Icing conditions do not mean necessarily ice accretion

Non running engine less prone to nacelle and fan icing

– Due to absence of fan airflow speed

But,difficult to assess conditions under which a non running engine will ice.

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F.A.Q.

Consequences if engine out taxi in icing conditions :

Possible delayed takeoff :

– If engine acceleration requested before takeoff

– Due to warm up , up to 5 minutes (depending on engine) before engine acceleration, on the last started engine

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F.A.Q.

Degraded control on slippery taxiway due to :Use of assymetric engine anti ice increases ground idle thrust

Conclusion :

Do not delay engine anti-icing, to avoid possible ice ingestion and engine damage

Engine out taxi not recommended if anticipated ice accretion

(freezing rain,freezing drizzle,freezing fog or heavy snow…)

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Contents

Introduction



F.A.Q. :

Do I need APU ?


Can I brake during engine start/shutdown on Can I brake during engine start/shutdown on S.A. ?S.A. ?


Conclusion

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F.A.Q.

On Single Aisle,why does Airbus recommend to not brake during engine start or shutdown, if the aircraft is moving ?

On A320 family,electrical transients

during engine start/shutdown– Automatic switch of BSCU channel

Alternate braking temporarily takes over

Greater braking efficiency in ALTN for same pedal deflection

Possible jerk if the aircraft is moving

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F.A.Q.

On Single Aisle,why does Airbus recommend to not brake during engine start or shutdown, if the aircraft is moving ?

(cont’d)

Braking is allowed during engine start/shutdown

FCOM wording clarified at next revision (sept 05) :

“during engine start or shutdown,a slight jerk forward may occur if brakes are applied when the aircraft is moving”

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Contents

Introduction



F.A.Q. :

Do I need APU ?



Can I perform the flight control check ?Can I perform the flight control check ?

Conclusion

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F.A.Q.

Can I perform the flight control check during an “engine out” taxi ( All FBW) ?

On a system point of view,no objectionGround tests found fully acceptable

But, recent isolated in-service event led to necessity of flight control check in takeoff configuration , in terms of electrical and hydraulic power.

Therefore with all engines started.

As all the failures cannot be automatically monitored

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F.A.Q.

Can I perform the flight control check during an “engine out” taxi ( All FBW) (cont’d) ?

New procedure to be incorporated to all FBW for commonality purposes :

Can be performed during engine warm up period.

The flight control check has to be performed after all engine starts, followed by the autobrake max selection.

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Conclusion

Engine out taxi already allowed (FCOM 3.04.90)

Helps to reduce :

Fuel consumption and CO2 emission

Brake wear

Turn around times

On SA,braking allowed during engine start/shutdown

Flight control check to be performed after all engines start

Documents

14 th Performance & Operations Conference Bangkok, 4-8 April 2005 One/two engine taxi Review of associated recommendations Presented by: Michel DOCUS Group