Single engine taxi-ing in a bus
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Single engine taxi-ing in a bus
I just wondering which airlines do this and in which Airbus types.Is it cost effective or do you just end up replacing more nose wheels?
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330 taxi inbound, shut down #2 after 2 minutes - helps save brakes as there is plenty of thrust on one to get you to the gate.
Minibus - don't bother - too much hassle
Minibus - don't bother - too much hassle
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A300 taxi inbound, shut down #1 after 2 minutes - helps save brakes as there is plenty of thrust on one to get you to the gate.
Minibus - don't bother - too much hassle
oops, it's #1
Minibus - don't bother - too much hassle
oops, it's #1
Last edited by hetfield; 10th May 2007 at 19:44.
Thread Starter
My employer wishes to introduce this for environmental reasons!Currently we have it approved for emergency use only.
Hetfield I think you operate the old bus at much lower weights than us,so I remain to be convinced.
Hetfield I think you operate the old bus at much lower weights than us,so I remain to be convinced.
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We now shut our minibus #2 down as soon as the APU is up and running, (on the ground ). The only complication is the yellow electric hyraulic pump to switch on, and hope you don't get changed to a fixed jetty.
). The only complication is the yellow electric hyraulic pump to switch on, and hope you don't get changed to a fixed jetty.
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We fly A319 to A321 and are encouraged to shut down No.2 if longer taxi-times are encounterd (i.e. waiting for the gate to be cleared) up to CPTs judgement.
During normal taxi-in (even during a longer one) it's rarely done, to much procedure, switching etc. and the a/c handling is far better on two, especially when heavy and you have to stop rather frequently.
Engine FF ist about 280 kg/hr in IDLE, the APU burns on ELEC only about 80 kg/h so for a 5 Minute-Taxi you could save some 15 kg. Theoretically. Maybe.
Regards, MAX (anti-beancounter)
During normal taxi-in (even during a longer one) it's rarely done, to much procedure, switching etc. and the a/c handling is far better on two, especially when heavy and you have to stop rather frequently.
Engine FF ist about 280 kg/hr in IDLE, the APU burns on ELEC only about 80 kg/h so for a 5 Minute-Taxi you could save some 15 kg. Theoretically. Maybe.
Regards, MAX (anti-beancounter)
Shut down number 2 taxing in (319,320,321) as soon as the APU is available and not going to a fixed jetty (319 only). Only have to turn on the yellow pump so not exactly complicated, quite agree that a heavy aircraft and lots of stopping is not ideal and I normally don't shut the engine down if I think that is going to be the case. It is probably the most effective fuel saving you can do on shorthaul to be honest, with longish taxi times (AMS 18R for instance) you can save 100kgs on one sector, hard to achieve that any other way.
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Also not sure why it is considered a particular hassle
APU on (at most places I will be doing that anyway) - so 1 extra button push (yellow hyd pump on) is all that is required. And that is only because the ptu is noisy and kepping yellow pressure prevents it from kicking in - but if you forget it isn't a major problem.
Even if you only save 15kg on a short taxi imagine if every 'bus operator saved that on every sector every day - no more complaining about it being hot in April!
(And factor in brake wear if you are light - someone told me that every time you apply ceramic brakes it costs about £5 in wear! Wasn't on airbus but that could really add up!).
APU on (at most places I will be doing that anyway) - so 1 extra button push (yellow hyd pump on) is all that is required. And that is only because the ptu is noisy and kepping yellow pressure prevents it from kicking in - but if you forget it isn't a major problem.
Even if you only save 15kg on a short taxi imagine if every 'bus operator saved that on every sector every day - no more complaining about it being hot in April!
(And factor in brake wear if you are light - someone told me that every time you apply ceramic brakes it costs about £5 in wear! Wasn't on airbus but that could really add up!).
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A320 Se Sop
A320 - After landing - 3min for thermal stabilization, then SE taxi. Yellow pump on, Eng Master 2 off (on CA's command when not using brakes), crossbleed open. No APU unless ground power not available at gate.
We've saved a lot of fuel since we implemented a SE taxi policy.
In the past, when taxiing for departure we were told not to use SE procedures unless the delay was over 40 mins. That was rethought and the policy now is SE unless the taxiway/ramp are contaminated or engine anti-ice is needed. Otherwise, time your #2 start to give yourself enough time for start, 2min warmup (if engine shutdown less than two hours prior), and all procedures and checklists.
We've saved a lot of fuel since we implemented a SE taxi policy.
In the past, when taxiing for departure we were told not to use SE procedures unless the delay was over 40 mins. That was rethought and the policy now is SE unless the taxiway/ramp are contaminated or engine anti-ice is needed. Otherwise, time your #2 start to give yourself enough time for start, 2min warmup (if engine shutdown less than two hours prior), and all procedures and checklists.
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No APU unless ground power not available at gate
I wonder why more dont do that. Here we have FEP at every gate, and the loaders plug it in straight away, but most foreign airlines have the APU running, and leave it running until all the pax are off. Our local airlines do not start the APU on arrival, in fact there is a note to this effect in the charts.
I wonder why more dont do that. Here we have FEP at every gate, and the loaders plug it in straight away, but most foreign airlines have the APU running, and leave it running until all the pax are off. Our local airlines do not start the APU on arrival, in fact there is a note to this effect in the charts.
Airbus has reversed the procedure on the minibus to shut down eng 2 first then select yellow elec pump on. Something to do with pump tripping off with the electrical transients when the engine is shut down.
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electrical transients when the engine is shut down
