One/two engine taxi презентация

Review of associated recommendations

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

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

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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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 / aircraft

Long Range :
average 2.5 cycles/day
250kg per day : 91250 kg / year / aircraft

Results based on 8 minutes with engine out
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

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

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

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

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 icing conditions ?
Can I brake during engine start/shutdown on S.A. ?
Can I perform the flight control check ?
Conclusion

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

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 icing conditions ?
Can I brake during engine start/shutdown on S.A. ?
Can I perform the flight control check ?
Conclusion

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

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.

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

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…)

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

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

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”

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

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

On a system point of view,no objection
Ground 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

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.

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