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Iceman49
7th Aug 2001, 08:17
Do other operators perform single engine taxi on the A320? If so what restrictions do you have. Our company tried it and found that we had significant wear on the engine that was started last and shut down first.

Bally Heck
7th Aug 2001, 13:59
Interesting Iceman.

My co are trialing SE taxi at the moment. What was the nature of the wear on the engine? Was a cooling off period allowed before shut down?

criticalmass
7th Aug 2001, 15:36
Guys, forgive me for not being an ATPL-holder, but what is the rationale behind a single-engine taxi on a twinjet like an A320 in the first place?

Airbus built it with two, the beancounters bought it with two, the public expect it to have two turning and burning and you're being asked to use one for taxying? I don't get it.

wysiwyg
7th Aug 2001, 18:52
Crit Mass - Some companies like one engine shut down as modern multi engine aeroplanes still produce so much residual thrust at idle while taxiing that the brakes have to be used to hold them back all the time. With a tight turnaround time you can run into problems adhering to the brake cooling schedules.

regards
wizzy

[ 07 August 2001: Message edited by: wysiwyg ]

NWSRG
7th Aug 2001, 18:56
Query from a simple PPL learner. What do you Airbus guys mean when you talk about FLEXing. I think this is something to do with power settings - am I right?

Old Dog
7th Aug 2001, 19:55
FLEX is short for Flexible Temperature Deration. It is the same thing as Assumed Temperature Deration. Different names adopted by different manufacturers.

Another case in point is N1 and EPR, different thrust reference for jet engines, but they are related through air densities (via temperature and pressure altitude).

Max Angle
7th Aug 2001, 21:27
We use single engine taxi-in on 737's but not A320/A321. It's up to the Captain anyway on the 737 and I never liked doing it. It feels very awkward, you have to hold quite a bit of tiller to make the a/c go straight. Can't be good for the nose leg and if you have to come to stop you need a lot of power to get it going again. The DC9 guys used to taxi out on one and then light it before take-off (hopefully!)

Iceman49
8th Aug 2001, 09:14
Bally Heck, I believe it was 2-4 minutes after it came out of reverse. I was asked why we didn't do it any more, since "everyone" did it...just wanted to get an idea if "everyone" did. Thanks

criticalmass
8th Aug 2001, 12:33
WYSIWYG,

Many thks for info. "I learned something about flying from that."

Might work well on something with closely-spaced engines like MD-80 and such but with wider-spaced engines I guess nosewheel tyres might well get scrubbed a fair bit. I guess tyres are cheaper than brake overhauls!

wysiwyg
8th Aug 2001, 12:54
I remember trying to taxi a light twin on one engine once (as it had to be moved and one engine wouldn't start) and it was very nearly impossible. I could only realistically turn towards the dead engine and trying to go straight ahead took nearly full rudder even though the aircraft was on tarmac. Then during my turboprop years it was standard practice (in my company) to shut down the left engine after a 2 minute cooling down period while taxiing in. This had the advantage that the left prop would be stationary by the time the passengers would have to walk past it during disembarkation, however on certain types you need to ensure that shutting down one particular engine won't compromise your hydraulic systems support for the main brakes or reserve brakes! While I'm sure there must have been some nosewheel scrubbing you really couldn't feel too much of a problem through the tiller. The only really important thing to remember was not to come to a halt at a point that would require pulling away combined with a turn into the live engine. In my current outfit we always taxi with both engines but then we plan on a 1 hour turnaround, so there is plenty of time for the brakes to cool before the next departure.

regards
wizzy

moleslayer
8th Aug 2001, 21:34
Airbus Flight Crew Operating Manual.
FCOM 3.04.90 One Engine Taxi.
Standard Operating Procedure. :)

Saves Brakes,Saves FUEL!!!

Phil Squares
8th Aug 2001, 22:25
My company, JetBlue, uses the single engine taxi procedure. At JFK, during the international push, you can save upwards of 400lbs...more if the wait is longer. Plus, there is considerable savings in break wear. Company leaves it up to the Capt is he wants to use the procedure or not. :cool: