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Old 17th Jul 2007, 14:33   #1 (permalink)
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Single-engine taxiing

I've never flown transport category aircraft (see my full and frank profile). I saw this passage below on an Airbus document and I'd like to understand the factors that go into whether you can or can't / should or shouldn't taxi single-engined.
Tks to anyone who has the time/inclination to help.
Taxiing with one (2) engine (s) out saves fuel but some drawbacks to be considered: operators must base their policy on airport config. (taxiways, runways, ramps
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Old 17th Jul 2007, 14:43   #2 (permalink)
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me neither, but i was looking at an A310 taxiing with one engine and then taking an acute turn onto stand(turning in the direction of the running engine). he really had to gun the engine to keep the thing rolling.
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Old 17th Jul 2007, 14:57   #3 (permalink)
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I do it as often as I can. Wish people wouldn't treat it as if it was the equivelant of a shuttle launch! ......especially if you go by the FCOM procedures on single engine taxy. My reasons are:-

1) Great EFP (overtime builder)
2) Saving wear and fuel on the engine
3) You hardly have to use the brakes saving on wear
4) Just doing my bit for the environment, small maybe but after watching Al Gores "An Inconvinent Truth" he states every bit helps.

The Cav
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Old 17th Jul 2007, 21:28   #4 (permalink)
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Works well on the 330 taxying in. Leave the engine to cool for a couple of minutes then shut #2 down. Doesn't race away like normal, saves brakes, just watch for upslopes and corners at the same time !
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Old 18th Jul 2007, 00:43   #5 (permalink)
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It's not taxying on one engine that worries me too much but those who taxy/coast onto the stand with no engines running!
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Old 18th Jul 2007, 00:54   #6 (permalink)
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It's simple on the 320. You can shut down the engine right away provided you haven't used more than idle reverse. As stated by others, it saves fuel and brake wear and the speed is much easier to control. On a long taxy (10 mins) it is possible to save about 80kgs of fuel which multiplied by each trip per year saves a lot of fuel and CO2 emissions. Airbus insists that the APU generator be on line before shutting down No2. This bit I could never understand. Must be afraid of problems on one generator unlike Boeing where it's not a problem. Now, starting one engine while taxying out is another question!
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Old 18th Jul 2007, 04:48   #7 (permalink)
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Am with you totally on that SIDSTAR. Am sorry to say that some of my fellow crew members (mostly management ) have been taxying out on one engine..............and when pushed to expedite have not been allowing sufficient warm up time before take off !

The Cav
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Old 18th Jul 2007, 05:53   #8 (permalink)
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I know the F Coms read as you have quoted, but logically dont you think the engines should be allowed a few minutes to cool before shutting down, as 50-60N1 on Approach is far more than idle reverse!

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Old 18th Jul 2007, 06:56   #9 (permalink)
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Single-engine taxi after landing is normal in my company. The things to consider before shutting down an engine are weight, airfield altitude, OAT and taxiway/ramp slopes. It's a bit pointless to shut one down if you will need 40% N1 on the other to keep rolling.

edited to add: Contamination on the taxiway/ramp is a factor as well. Some years ago I taxied in at Stockholm with one shut down. We had to stop short of the stand to wait for the parking guidance to be switched on. Unbeknownst to me, the nosewheel had come to rest on a patch of ice (it was dark). When I wanted to move again, I applied power and the aircraft swung right. The nose wheel steering had no purchase on the ice; consequently there was no directional control. We shut down and were towed the last 20m.

I don't worry about CO2 emissions. It's a load of old cobblers ...

Last edited by Wingswinger; 19th Jul 2007 at 10:38. Reason: addition
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Old 19th Jul 2007, 10:00   #10 (permalink)
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It is a challenge. And a safe one to take too. The only safety related issue is to be very carefull who is behind you if you have to increase your thrust one the running engine. So as a rule, I avoid it in small aprons.

The other (non safety related) danger is loosing face. I must admit I had a couple of almost embarassing moments while I unexpectedly was asked to hold position by ATC on an upslope part of the taxiway. Practice and experience makes perfect. Especially now that my SOPs allow me to restart the engine if I get in trouble. Better that than a tug....
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Old 19th Jul 2007, 11:30   #11 (permalink)
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Single engine taxi

Just don't forget to put the APU on first and then the 'Y' HYD PUMP on A320 family
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Old 19th Jul 2007, 11:35   #12 (permalink)
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Wingswinger, Very good point re its useless if you need 40% on the remaining engine to get the old girl going. I fly a Boeing and a way we do it is to shut down the #2 engine BUT

1) Start APU. Instead of leaving the #1 bleed ON, open the isolation valve and CLOSE the engine bleeds.

By using the APU for air the live engine has a lot more residual thrust and very rarely one needs to apply thrust to the live engine to maintain adequate speed.

L Met
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Old 7th Aug 2007, 00:16   #13 (permalink)
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Single engine taxi out : Departure

Could someone report on their experience single engine taxi out/departure.

We just started doing it.

How do you do the task sharing ?

Do you do it while moving or stopped with the parking brake set at the holding point which can cause obvious problems and delays ?

Is the minimum two minutes enough to take off after starting engines ?

Do you really save 80 kg each time with the APU on ?
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Old 18th Aug 2007, 15:12   #14 (permalink)
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Airbus has just changed the order of the procedure to read APU on, then Eng 2 shutdown, then Y Hyd pump on. Eng shutdown and Yellow pump on have been reversed due to a possible problem with the pump shutting down during the electrical changover and not coming back on line when the APU is on the bus.
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