One/two engine taxi

1. One/two engine taxi

14th Performance & Operations Conference
Bangkok, 4-8 April 2005
Presented by:
Michel DOCUS
Group Manager A320 Family
Operational Standards
One/two engine taxi
Review of associated recommendations

2. Contents

Introduction
Why should I perform an “engine out” taxi ?
Conditions to perform an “engine out” taxi
F.A.Q. :
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
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
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

3. Introduction

Increased use of one or two engine out taxi
Taxi time increases due to :
Airport
congestion
Increased
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
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
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

4. Contents

Introduction
Why should I perform an “engine out” taxi ?
Conditions to perform an “engine out” taxi
F.A.Q. :
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
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
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

5. Benefits of engine out taxi

© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
Benefits of engine out taxi
Reduce CO2 emission (Kyoto protocol)
Save fuel
Save brakes
Reduce turn around time
Airport regulations
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

6. Benefits of engine out taxi

Reduce CO2 emission
Kyoto
protocol valid since 16 feb 2005
– Reduce CO2 emission to 1990’ level
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
– 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
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

7. Benefits of engine out taxi

Fuel economy :
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

8. Benefits of engine out taxi

Fuel economy per aircraft :
Single Aisle :
– average of 4.5 cycles/day
– 180kg per day : 65700
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
Long
kg / year / aircraft
Range :
– average 2.5 cycles/day
– 250kg per day : 91250
Results
Taxi
One/two engine taxi
kg / year / aircraft
based on 8 minutes with engine out
on some airports may reached 45 minutes !!!
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

9. Benefits of engine out taxi

Brakes saving
Lower thrust
Lower taxi speed
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
Reduced number of brake application
Brake saving
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

10. Benefits of engine out taxi

Reduced turn around time
Reduced brake temperature
Prevent “Brakes Hot” warning
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
Less takeoff delays
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

11. Benefits of engine out taxi

Airport regulations
To
enhance safety but shutting down the engine near the air
bridge
To reduce Noise
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
– ”Getting to Grips with Aircraft Noise” brochure
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

12. Contents

Introduction
Why should I perform an “engine out” taxi ?
Conditions to perform an “engine out” taxi
F.A.Q. :
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
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
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

13. 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
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
Slow
or tight taxi turn more difficult at high gross weight
Not recommended on slippery taxiways
More
One/two engine taxi
difficult to steer with asymmetric thrust
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

14. Airbus recommendations before applying engine out taxi

Respect of the engine stabilization times
Minimum
To
thermally stabilize the engine hot sections
In case of mechanical event,return to the gate may be
required for maintenance action
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
of 2 min engine warm up and 3 min cooldown time
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

15. Contents

Introduction
Why should I perform an “engine out” taxi ?
When should I perform an “engine out” taxi ?
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
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
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

16. 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
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
Minimizing APU
use helps save fuel and reduces maintenance
– APU max consumption : between 125 (SA) and 290 kg/hr (A3456)
But APU
One/two engine taxi
is not necessary for engine out taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

17. Contents

Introduction
Why should I perform an “engine out” taxi ?
When should I perform an “engine out” taxi ?
F.A.Q. :
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
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
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

18. F.A.Q.

Can I perform engine out taxi in icing conditions ?
FCOM / AFM :
Engine
anti ice must be on
when icing conditions exist
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
or are anticipated:
– To avoid ice accretion on
nacelle and fan
Engine
One/two engine taxi
anti ice operative only on a running engine
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

19. F.A.Q.

In icing conditions,non running engine will not necessarily ice :
Icing
Non
conditions do not mean necessarily ice accretion
running engine less prone to nacelle and fan icing
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
– Due to absence of fan airflow speed
But,difficult to assess conditions under which a non running
engine will ice.
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

20. F.A.Q.

Consequences if engine out taxi in icing conditions :
Possible
delayed takeoff :
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
– 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
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

21. F.A.Q.

Degraded control on slippery taxiway due to :
Use
of assymetric engine anti ice increases ground idle thrust
Conclusion :
not delay engine anti-icing, to avoid possible ice ingestion and
engine damage
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
Do
Engine out taxi not recommended if anticipated ice accretion
(freezing rain,freezing drizzle,freezing fog or heavy snow…)
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

22. Contents

Introduction
Why should I perform an “engine out” taxi ?
Conditions to perform an “engine out” taxi
F.A.Q. :
Do I need APU ?
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
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
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

23. 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
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
– 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
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

24. 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)
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
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”
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

25. Contents

Introduction
Why should I perform an “engine out” taxi ?
Conditions to perform an “engine out” taxi
F.A.Q. :
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
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
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

26. F.A.Q.

Can I perform the flight control check during an “engine out”
taxi ( All FBW) ?
On a system point of view,no objection
Ground
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
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
As
One/two engine taxi
with all engines started.
all the failures cannot be automatically monitored
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

27. F.A.Q.

© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
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 :
The flight control check has to be performed
after all engine starts, followed by the autobrake
max selection.
Can be performed during engine warm up period.
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005

28. Conclusion

Engine out taxi already allowed (FCOM 3.04.90)
Helps to reduce :
Fuel
consumption and CO2 emission
© AIRBUS 2005 S.A.S. All rights reserved. Confidential and proprietary document.
Brake
Turn
wear
around times
On SA,braking allowed during engine start/shutdown
Flight control check to be performed after all engines start
One/two engine taxi
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14th Performance & Operations Conference Bangkok, 4-8 April 2005