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N62NA
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Taxi On 1 Engine?

Thu Dec 02, 2004 1:29 am

With the price of fuel so high, why don't the airlines institute a new policy of taxiing out to the runway on just 1 engine? I've been on CO ATRs back in the 90s and remember they were able to do it?

Are there operational reasons why jet aircraft don't do this?
 
SlamClick
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 1:40 am

Can't answer for any turboprop aircraft but I'd say that just about every airline in the US has a policy of taxiing jets in and out on one engine whenever possible.

Happiness is not seeing another trite Ste. Maarten photo all week long.
 
Okie
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 1:46 am

Taxi on one engine is pretty much common practice these days.

However, if taxi times are estimated to be short all engines are usually started at the gate/ramp area.

I believe that most engine manufacturers prefer about a 5 minute warm up before bringing the engine up to take off power.

In the last couple of years I have not noticed many multi engine taxi except on turbo prop type air craft.

Okie
 
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N62NA
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 2:04 am

That's good to know, and here I thought that all that fuel was being wasted. So basically, while all engines are running the pilot only moves a single lever corresponding to a single engine forward for taxi power?
 
HaveBlue
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 2:09 am

No, they actualy have the other engines off, not at idle.
 
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N62NA
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 2:18 am

Interesting. Could have sworn on all my AA flights (40+ roundtrips this year) that I've always heard the engine on 1 side start up, then the engine on the other side start up and then we began our taxi.

I'll pay closer attention on my next flight in 2 weeks from now!
 
avt007
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 2:53 am

At Canadian Regional, (now Jazz) the policy for jets and props was to taxi on both engines since they did not want to risk having a problem crop up in the line up for the runway. For example, an autofeather snag, or a generator, or any other possible fault. And every AC and LH flight I take these days starts all engines after pushback. AirBC ( now also Jazz) once made the classic error of taxiing on 2 engines on a Dash7 , and forgetting to start the remaining 2 engines for takeoff. That may be a BS story, but I have talked to an eyewitness, so be careful folks!
 
AAR90
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 6:34 am

Interesting. Could have sworn on all my AA flights (40+ roundtrips this year) that I've always heard the engine on 1 side start up, then the engine on the other side start up and then we began our taxi.

AA has an agressive single-engine taxi policy; however, there are many situations where single-engine taxi is not advantageous or even possible. Most often the terminal layout (nearness of objects/people/etc.) requires use of both engines to initiate taxi. If that's the case it is often not advantageous to single-engine taxi due to operating limitations (i.e. 3-minute warm-up and 3-minute cool-down time limits on B738).
*NO CARRIER* -- A Naval Aviator's worst nightmare!
 
LMP737
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 8:35 am

AAR90:

Here on the maintenance side of the house we try and do single engine taxis. Well, at least some of us do. The 777 requires both engines for taxi. If you were to use just one some serious damage could result when you throttled up to break away power.
Never take financial advice from co-workers.
 
ScooterTrash
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 8:44 am

On the Dash 8 I always taxi out on one engine unless:

- I need a sharp right turn to get out of/into the gate.

- There is snow/slush or other slippery matter on the taxiway.

- I have an ECU, antiskid, nosewheel steering inop (or any other MEL item which would proclude single engine taxi).

- The taxi will be less than 5 minutes.

When doing the single engine taxi procedure we taxi with the number 2 engine. Apparently, using number 1 is worse on the nosegear, but I couldn't tell you why.

Scooter
 
2H4
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 10:44 am

Apparently, using number 1 is worse on the nosegear, but I couldn't tell you why.


Strange that there would be a lateral variation in strength/durability on a nose gear.


2H4
Intentionally Left Blank
 
avt007
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 11:08 am

Scooter- I used to be a reliability rep for the Dash8 at CRA. This nose gear strain issue was brought up, and basically a long time ago there was an issue with cracks in the NLG, and someone put it down to taxiing on one engine. The reps from Bombardier clearly stated there was no problem and no strain on the NLG taxiing with any combination of engines. Personally I always used two, and we did a ton of taxiing, basically at least two aircraft a day.
 
KYIPpilot
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 11:58 am

I heard a NW DC-9 pilot say that on average, taxiing a DC-9 on one engine would save about 2000 pounds of fuel for every flight. If every NW DC-9 did that everyday, think of the fuel savings.
"It starts when you're always afraid; You step out of line, the man come and take you away" -Buffalo Springfield
 
AAR90
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 12:29 pm

that on average, taxiing a DC-9 on one engine would save about 2000 pounds of fuel for every flight.

I seriously doubt that "average" figure. Normal ground idle fuel flow is <1,000 lbs/hour so 2,000 lbs equates to about 2 HOURS of taxi time. Not likely NW averages 2 hours of taxi time per DC-9 flight. OTOH, the small fuel used reduction (and it really is a small amount of fuel saved per flight) quickly adds up when you realize a couple thousand flights per day... 7 days per week... 52 weeks per year....
*NO CARRIER* -- A Naval Aviator's worst nightmare!
 
LineMechQX
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 12:31 pm

At QX single engine taxi's are not allowed in the Q400 aircraft, due to the stress on the nosegear. From what I understand this idea begin with the 200's (which is allowed). But due to the length of the long tubes it was deemed too risky from the powers that be. In fact you won't hear the pilots feathering the number one on the way into the gate, as they often do for the 200's just for this reason.

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avt007
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 2:07 pm

LineMechQX- you have a good point on the 400, I never had the chance to work on one, but with the extras length it could be an issue. But as for fuel savings, I guess they add up, but IIRC, the 300 burns 250 lbs per hour at flight idle, so it isn`t a huge amount.
 
lowrider
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RE: Taxi On 1 Engine?

Thu Dec 02, 2004 3:22 pm

Not all aircraft are set up for single engine taxi. For example, nose gear steering and brakes may be powered by seperate hydralic systems or may require two or more systems on line for normal operation. I would imagine that most transport catagory aircraft produced in the last 15 to 20 years or so would at least have work arounds for this issue, though.

I know it is my company's policy to utilize SE taxi when ever it is consistent with safety. Every little bit of fuel helps.
Proud OOTSK member
 
ScooterTrash
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RE: Taxi On 1 Engine?

Fri Dec 03, 2004 12:17 am

AVT007:

Yeah, that's one area where our mx troops disagree with Bombardier. Taxiing on the number 1 engine is strictly verbotten in our manual.

The folks that say that taxiing on one engine saves lots of money are definitely correct. The Dash costs about $36/minute on the ground to run, so you cut that about in half with one motor running. Just be sure that number 2 AC generator is on!

Scooter
 
avt007
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RE: Taxi On 1 Engine?

Fri Dec 03, 2004 1:43 am

Scooter- does that figure include your salary?  Big grin Taxiing for mtce purposes was our call, we were encouraged to taxi on two, personally the cost didn't worry me, but the added control and safety and convenience meant I always used two, unless we had a fuel nozzle change, or something similar to do that night, In that case, we'd use the other engine, so we'd have a cool engine to work on. Those things take forever to cool down enough!
 
flyboy1980
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RE: Taxi On 1 Engine?

Mon Dec 06, 2004 6:45 pm

Air New Zealand ATR-72-500's routinely taxi on one engine, both on departure and arrival.

As cabin crew it was funny to watch the pax's faces...staring at the engine that wasn't running while waiting for take off...look at the engine...stare anxiously at cabin crew....look at engine...

One cabin crew told a pax that as the flight was only half full, we only needed to use 1 engine! He was a Cabin Crew trainer too!  Smile
 
ngr
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RE: Taxi On 1 Engine?

Tue Dec 07, 2004 12:34 am

I flew on Delta airlines over Thanksgiving, and on 3 out of 4 flights, we taxied on one engine for approximately half of the taxi time. The aircraft this was performed on were the MD-88 and 737-200. On the MD-88, the left engine was always started first, appearantly because it operates the systems necessary for taxi....I say this because I noticed that the ailerons were "drooping" and I was concerned about this at first, but as soon as the right engine was started, the flaps and ailerons returned to their "normal" positions. After landing, the right engine was again shut down, and we taxiied on the left.

I only flew once on the 737-200 where we taxiied on one engine, but the right engine was started first, and shut-down first, so it is my observation that it can taxi on either engine.

I am not 100% sure about this, but I believe this practice has become common for Delta because I saw several other aircraft...especially the ATR-72s...taxiing on only one engine.

Please feel free to correct me if I have made an error in any of the above...

 
AAR90
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RE: Taxi On 1 Engine?

Tue Dec 07, 2004 12:49 am

On the MD-88, the left engine was always started first, appearantly because it operates the systems necessary for taxi....I say this because I noticed that the ailerons were "drooping" and I was concerned about this at first, but as soon as the right engine was started, the flaps and ailerons returned to their "normal" positions.

MD80 series planes have no "drooping" ailerons and the hydraulic system is powered by electric pumps whenever the engine pumps are not operating. I believe the left engine is normally used due to bleed air configurations (it has been a few years since I last piloted a MD bird). If memory serves, the left engine is "farthest" from the APU bleed air source and can be isolated permitting right engine start without securing left engine bleed air (also permits both A/C packs operating with different air sources for each).

For 738 (don't know about earlier models) it is the opposite (right engine start first) also due to bleed air plumbing. Once the right engine is operating you can isolate it to run the right pack and use APU to run the left pack (permits one pack operation even during left engine start). Procedurally it is the recommended configuration for all single-engine ground ops; however, I often shut down the right engine after landing to protect ground troops from getting too close to an operating engine during parking (cargo doors on the right side).
*NO CARRIER* -- A Naval Aviator's worst nightmare!
 
IL76TD
Posts: 280
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RE: Taxi On 1 Engine?

Tue Dec 07, 2004 2:57 pm

here in SHJ i've seen plenty of Tupolev three holers taxi between the terminal area and mx area using only the center engine. How do i know? Well for one they don't even bother removing the inlet covers from the outboard engines.
 
modesto2
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RE: Taxi On 1 Engine?

Sat Dec 11, 2004 3:14 am

Anyone who's departed JFK in the early evening can relate to this experience... I was on JetBlue this past summer and with a 45 minute wait for a 22R departure, the pilots made an announcement that we'd be taxiing on one engine.

Side note that's not really related but was on a UA A320 and the APU was INOP so we did a cross-bleed start on the taxiway. Technically, that constitutes a one engine taxi but for other reasons.

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