Engine Out Taxi on Departure.

[Ozeflyer]

I have been asked to look into B744 taxi on departure with suspected long taxi with one or maybe two engines shut down and then started prior to departure.

Anyone out there doing this on the 400?

[ACMS]

I'd go to the North American site and ask there. UA is bound to do that sort of thing all the time.

We did it on the 77W in JFK a few times.

[ACMS]

77W FCTM--

ENGINE OUT TAXI

Refer FCOM 3.

Engine Out Taxi (EOT) operations have the potential to save fuel and to reduce carbon emissions.

During EOT operations, the crew's attention should be focused on taxiing the airplane. Distractions should be kept to a minimum.

High bypass engines require warm-up prior to applying take-off thrust and cool down prior to shutting down. If the engine has been shut down for several hours, it is desirable to operate at as low a thrust setting as practical for several minutes prior to take-off.

If an engine is shutdown during taxi in after flight, the crew must be aware of hydraulic, electrical, and braking system requirements, particularly any degraded system operation due to enroute failures.The APU should be operating while taxying with an engine shutdown. If possible, make minimum radius turns in a direction that puts the operating engine on the outside of the turn. In operational environments such as uphill slope, soft asphalt, high gross weights, congested ramp areas, and wet/slippery ramps and taxiways, taxi with both engines operating.

[ACMS]

FCOM 3

Engine Out Taxi

In all cases, two engines shall be started for the initial taxi out. Should a protracted ground delay be expected or occur prior to takeoff, it is permissible to shutdown any or both engines.

The APU should be operating while taxiing with an engine shutdown.

Assess the operational environment and consider possible blast damage from higher than normal thrust requirements when taxiing with one engine at high gross weight.

Engine out Taxi operations should not be conducted when a system that impacts braking or steering capability is not operative.

For restart, when the aircraft is stationary accomplish the BEFORE START and BEFORE TAXI Checklists, together with the associated procedures.

[ACMS]

Something relevant to get you thinking.

[Skyjob]

For twin engined aircraft, there may be operational limitations not to taxi on a single engine BEFORE departure, such as on the 737, which only recently received Boeing approval to enable such actions subject to approval and establishment of operator procedures.

This is due to the fact the takeoff weight is substantially higher and would require significantly more thrust to start moving once a full stop during taxi has been made. This could also apply to other twins on the market, especially those going longer and further.

On the 747, or other quads or even tri's, the case of taxiing on two engines is not as rare, especially with prolonged ground delays, however once again, due to the increased weight before departure, this may have some operational restrictions and limitations.

[tdracer]

There are a few North American operators that use (or at least used) both departure and arrival single engine taxi as SOP on their 757s, and I've been on Asian based 777s where they shutdown one engine shortly after landing and taxied in on one.


Many years ago, an operator came in and wanted us to put up an EICAS message telling them the engine had been at idle for 5 minutes and they could shut it down. We asked what sort of logic should we use for initializing the timer (since our flight ops said we could only display the message when the crew was expected to shut down the engine).
Request quietly went away :ugh:

[Tinwacker]

Asian based 777s where they shutdown one engine shortly after landing and taxied in on one.

Company routine after sufficient cooling down time has been achieved for fuel saving, same for the B744..

EICAS message 'PRESS STOP WATCH'......

[Intruder]

Allowed at our company for 3 engines <330T and 2 engines <300T. I seldom do it (as in, twice in 8 years) because of the interruption of normal routines. Also, 1 engine shutdown gives little savings if the APU remains running, and you cannot assume clearance behind to run up an engine.

[Ozeflyer]

Thanks for all the input. Our engine provider is the one who has suggested we look at this and pretty sure it will happen when we get the details sorted out.

[bigduke6]

With 2 engines at idle at elevations close to sea level, and only 1 pack running, you can start the other 2 engines (one at a time!) with the the available duct psi....no need to leave the APU running or advance power for a cross bleed start.

[Intruder]

On the 744, generally true for the P&W engines, but not the GE CF6.