A ? for Boeing and Airbus guys...

ozziecat35

ozziecat35

4 out of 5 great lakes prefer Michigan.
So at work today I realized one standard as a ramp agent...whenever I'm pushing out a 737, the crew always wants to spin #2 first.....though when I'm pushing a 319 / 320 / 321, it's always #1...

Any one have a good reason, or is it probably just something taught in the sim that has stuck with them?

Cheers,
Matt
 
Probably depends on which system the nosewheel steering is. I know on the 145 it's on system 1 which is tied to engine 1 which is why engine 2 is always started first during a pushback, we wouldn't want to put 3000psi of pressue on the nosewheel and potentially kill anybody in the "way"
 
Chris_Ford said:
Probably depends on which system the nosewheel steering is. I know on the 145 it's on system 1 which is tied to engine 1 which is why engine 2 is always started first during a pushback, we wouldn't want to put 3000psi of pressue on the nosewheel and potentially kill anybody in the "way"
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That was what I was thinking at first, but then what would be the point of a bypass pin? I mean I clear the guys to turn the engines once I have the nosewheel off the block, so no one would be anywhere near the nosegear.
 
On a B757/B767 it doesn't make any difference except most of the time we'll start the left engine first on a 757 because of a power transfer unit that kicks in with the left engine shut down that gets very noisy. On a B767 most of the time it's the left engine...for the hell of it...but I see a considerable number of captains that will start an engine that makes the initial turn out of the gate easier.

On a B737, I believe there's hydraulic and electric generator issues associated with that airplane...but it's been almost nine years since I've flown it and can't remember precisely.
 
My personal opinion is that it's a matter of brakes and steering.

In my experience you always start the engine (on twins) that supports the nosewheel steering.

FWIW, on the 747, we taxi out on 1&4 as that supplies the brakes and steering.

In any case, you have an engine driven pump, and your back up pump to support the steering and braking. Were you to start other combinations, you are using your backup pump to operate the system. If that fails, you're filling out paperwork.
 
Not Boeing or Airbus, but on the CRJ was start the right first because one of the brake systems is tied to that side's hydraulic system. The other brakes systems are off the AC Hydraulic system, so that way we have both sets of brakes. There is a work around (turning on the backup AC pump on the right side system) but it's not really procedure to do it that way.
 
meritflyer said:
I know on the Turbo Arrow I fly.. Er... Whoops, wrong thread. ;)
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yeah, try as I may to incorporate my 99.4 hrs of Cessna and Cirrus experience...I couldn't make a logical connection, lol...:p

Thanks for all the responses gents....the more I think about it, I agree it's probably a system issue running off of a certain engine...one of these days I'll go talk shop with the drivers up front.
 
Might be because of the air conditioning system on the 737 as well. If you crank the left, you could run use the APU to run the left pack and the right engine to run the right while the... oh geez, what in the hell was that thing called again...OH! the isolation valve was closed.

I've only got about 800 hours of -200 time so my memory may have failed me.
 
Polar742 said:
My personal opinion is that it's a matter of brakes and steering.

In my experience you always start the engine (on twins) that supports the nosewheel steering.

FWIW, on the 747, we taxi out on 1&4 as that supplies the brakes and steering.

In any case, you have an engine driven pump, and your back up pump to support the steering and braking. Were you to start other combinations, you are using your backup pump to operate the system. If that fails, you're filling out paperwork.
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You guys taxi out on 2 engines? Is that SOP or is it a weight and wait thing?

FWIW, our sequence is 4,1,2,3 mainly for brakes and body gear steering during the push so we can alleviate the pressure on the ADPs as soon as possible. I can't imagine getting a heavy freighter to move on two engines, you guys are braver than I am!
 
Granted it's a virtual light twin, we taxi the 767-300 on one engine, at times, over 400K #'s.
 
Doug is basically right. On the 737, you are able to isolate the #2 engine and right air conditioning pack from the rest of the pneumatic system. If you taxi out on one engine, starting the number two engine first allows you to run the right pack with the #2 engine and the left pack with the APU bleed. If you are starting them both up, starting the #2 engine first allows you to get air conditioning going right away by isolating the number two side while starting the #1 engine with APU bleed air. Taxiing out on the #1 engine would give you the option of running the left pack or the right pack, but not both. That's why you see so many who start the #2 engine first.

I always ask about late bags before starting the #2 engine as the cargo doors are on the right side of the aircraft and the #2 engine would need to be shut down to accommodate any late bags.
 
Do the newer generation 73's work the same way? I've only dealt with the -200's.
 
Doug Taylor said:
Do the newer generation 73's work the same way? I've only dealt with the -200's.
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Yes, they still have the isolation valve that enables isolating either side. On the new 737s (-700, -800 and -900) you can run both packs from the APU which you couldn't do on the classics. If you choose to on the newer 73s, you can close both engine bleeds and run both packs from the APU - then it wouldn't matter what engine you taxied out on as you would have two packs running. The preferred method is to run the left pack off the APU and the right pack off the #2 engine as you get significantly more airflow from two independent sources.
 
Ahh, I see. Something different on the 75/76 is that if we're single-engine taxiing, we'll bleed off the APU for both packs. On the mad dog, generally we'd bleed on pack off the engine and the other off the APU unless we're going to perform a cross-bleed.

TMI, yes, I know! ;)
 
ozziecat35 said:
So at work today I realized one standard as a ramp agent...whenever I'm pushing out a 737, the crew always wants to spin #2 first.....though when I'm pushing a 319 / 320 / 321, it's always #1...
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Hm. I thought the 320's started #2 first, but anyway...

I think that the A320's always start the same engine the first time because that one powers the Green Hyd Sys, which powers the normal brakes. Don't know about the 737.
 
Doug Taylor said:
Ahh, I see. Something different on the 75/76 is that if we're single-engine taxiing, we'll bleed off the APU for both packs. On the mad dog, generally we'd bleed on pack off the engine and the other off the APU unless we're going to perform a cross-bleed.

TMI, yes, I know! ;)
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Back in my 757 days, we didn't have the option of single engine taxi so I didn't have to think too hard on how to configure the air. I guess $3.50 jet fuel makes one re-think the single engine taxi concept. Although, I am not so sure that running one engine up to 40 or 50 percent just to get the aircraft moving is that cost effective over just starting two initially. I know the guy behind me doesn't like it when I taxi my heavy airplane with one engine. :panic:
 
calcapt said:
I know the guy behind me doesn't like it when I taxi my heavy airplane with one engine. :panic:
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The 757/767 idles above 70% N2...doesn't take much of a bump to get the airplane moving...and you can accomplish a crossbleed start with the operating engine at idle. Single engine ground ops is no biggy...unlike all narrowbodies I've flown that require some sort of static runup just to get pneu pressure.

Actually, 2 engine taxi will probably require you to ride the brakes.
 
rjmore said:
You guys taxi out on 2 engines? Is that SOP or is it a weight and wait thing?

FWIW, our sequence is 4,1,2,3 mainly for brakes and body gear steering during the push so we can alleviate the pressure on the ADPs as soon as possible. I can't imagine getting a heavy freighter to move on two engines, you guys are braver than I am!
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It's a weight and wait deal. On the 74RJ, our long haul flight ICN-HKG still has us at or about MLW, even with a full boat. The other route, ICN-PVG, is about 35k kilos. (We do everything in kilos). I did see a performance calc that required a 1 minute fuel dump for a return ;) We were heavy that day.

Of course it's PIC discretion, so I start as many as I'm told :D

>330k 4 motors
300-330 3 motors
<300 2 motors

As a side note, it costs the company $20/min/eng during taxi out. I sure enjoy having my CBA complied with....

There's no "proper" sequence we use, on the classic we have an electric pump for brakes on HYD4 and use the ADP on 1. All F/E controlled. None of this "Automagical" sissy stuff. (At least til this fall ;))

With the classic we have the steel brakes, so they get hot, and it shuffles fast with 4 turning at light weight.

Have the body gear steering MEL'd yet? It's freaky to feel it hop in turns!!
 
Doug Taylor said:
Do they at least "free caster" or do they just sit there?
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On the classic, if operating properly, they turn when the nosegear exceeds 20 degrees. Makes lining up interesting, at least till I get some more time in it.

When MEL'd they're locked straight. Otherwise, there'd be no guarantee they'll fit in the wells.

U-turn goes from 153' to 170'
 
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