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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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One/two engine taxi 3 14th Performance & Operations Conference Bangkok, 4-8 April 2005
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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One/two engine taxi 4 14th Performance & Operations Conference Bangkok, 4-8 April 2005
Contents
Introduction
Why should I perform an “engine out” taxi ?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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One/two engine taxi 5 14th Performance & Operations Conference Bangkok, 4-8 April 2005
Benefits of engine out taxi
Reduce CO2 emission (Kyoto protocol)
Save fuel
Save brakes
Reduce turn around time
Airport regulations
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Benefits of engine out taxi
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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One/two engine taxi 7 14th Performance & Operations Conference Bangkok, 4-8 April 2005
Benefits of engine out taxi
Fuel economy :
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Benefits of engine out taxi
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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Benefits of engine out taxi
Brakes saving
Lower thrust
Lower taxi speed
Reduced number of brake application
Brake saving
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One/two engine taxi 10 14th Performance & Operations Conference Bangkok, 4-8 April 2005
Benefits of engine out taxi
Reduced turn around time
Reduced brake temperature
Prevent “Brakes Hot” warning
Less takeoff delays
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One/two engine taxi 11 14th Performance & Operations Conference Bangkok, 4-8 April 2005
Benefits of engine out taxi
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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One/two engine taxi 12 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 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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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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One/two engine taxi 15 14th Performance & Operations Conference Bangkok, 4-8 April 2005
Contents
Introduction
Why should I perform an “engine out” taxi ?
When should I perform an “engine out” taxi ?
F.A.Q. :F.A.Q. :
Do I need APU ?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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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
Why should I perform an “engine out” taxi ?
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 ?
Can I brake during engine start/shutdown on S.A. ?
Can I perform the flight control check ?
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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One/two engine taxi 22 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 Can I brake during engine start/shutdown on S.A. ?S.A. ?
Can I perform the flight control check ?
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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One/two engine taxi 25 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 ?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