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FromTheFlightDeck_Sim

Is it necessary to start the starboard engine first?

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I was trying to startup the NGX this morning, did the correct procedures said by the checklist, until I began to start the engines. I ignited the LEFT engine first, and it spooled up perfectly. Then I began to ignite the RIGHT engine next, and the N2 showed no power on the right engine.

 

Lately I've been hearing that the right engine has to be started up first. Why, and will it solve my problem?

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Which engine is started first can vary by operator or conditions, many airlines do use an engine 1, 2 starting procedure as a standard. Starting engine 2 first though lets you isolate a pack which helps with cabin heating or cooling on really hot or cold days.  Double check your isolation valve is open, the left engine and the apu bleed are on the same side of this valve which may be why engine 2 isn’t starting for you.

 

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Yeah I bet the source of your problem is not starting 1 first.

 

Many a time I have started 1 first, such as if a slight fuel imbalance exists. And if you always start 2 then 1 then you better shut it off first too or you will slowly accumulate more time on number 2. Some carriers like this sequence so that the ground crew can get to work on the baggage for a quicker turnaround.

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The airline that I worked for started Boeings, 2 then 1. Airbuses 1 then 2.

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Yeah I bet the source of your problem is not starting 1 first.

 

Nah, unlikely. You may start both at once if you wish, or 1 first, or 2 first, or hold your right thumb in your left hear...it won't make a difference:p

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Nah, unlikely. You may start both at once if you wish, or 1 first, or 2 first, or hold your right thumb in your left hear...it won't make a difference:p

I think I tried that once and there wasnt enough air to get N2 going on both. I have seen on videos 747s starting 3 and 4 at once but the little APU on the NG can it get both going at the same time ?

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As mentioned above, the start sequence will depend to a certain extent on operator SOPs and also the aircraft systems (ie: type specific). Historically I think the No 2 (starboard) engine has tended to be started first because normally boarding is from the left hand side of the aeroplane: therefore, the No 2 engine is in theory furthest away from any ground equipment/steps etc etc and so starting it first during the pushback meant that by the time you got round to starting the No 1 (port) engine you would be a bit further away from the jetbridge etc (or, indeed, in some cases (particularly in the really old days), you could have started #2 (or #3 and #4) whilst still boarding on the port side of the aircraft).

 

However, it does depend a little on the type:

 

 


The airline that I worked for started Boeings, 2 then 1. Airbuses 1 then 2.

 

On the A320, the No 1 engine powers the Green hydraulic system, which (in most MSNs) powers normal brakes and nosewheel steering. Both are quite useful things to have (especially if you are planning on carrying out a single-engine taxi) and so it makes sense to start #1 first in this case. Conversely on the 747 brakes and steering are provided by the #1 and #4 hydraulic systems and so if you were going to conduct engine-out taxi on the 747 then either #3 or #2 and #3 would be shut down, leaving #1 and #4 running.

 

 


I have seen on videos 747s starting 3 and 4 at once but the little APU on the NG can it get both going at the same time ?

 

Indeed, it is common practice on the 747 to start two at a time (usually #3 and #4, then #1 and #2), except in certain circumstances (high temperature and/or high altitude starts, where either individual autostarts or individual manual starts are necessary).

 

I don't know about the 737 APU but I doubt it has enough "puff" to start both simultaneously.

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I don't know about the 737 APU but I doubt it has enough "puff" to start both simultaneously.

 

No, it was always one engine and then the other. The only time we started #1 first on a Boeing was when we were doing an air start. That was for the safety of the ramp personnel. Some pilots complained but we told them it was that way or you're not going anywhere.

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I don't know about the 737 APU but I doubt it has enough "puff" to start both simultaneously.

 

On one hand it's possible but on the other there's no reason to..., make sure both packs are off then there's enough "puff" unless density altitude is high.  Dual start is just showing off and no one is doing it unless it is your BBJ.

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So to simplify, starting #2 first is recommended?

The bleed air sources for engine start are: APU, Ground cart or the other engine.

Using APU, normal start sequence is 2 and then 1 (Boeing recommendation). As you can see from the diagram

(http://www.b737studyguide.com/B737NGiPad/AirSystemsSGR/PneumaticSystem_800_iPad.html ) APU is connected to the left side of the bleed air system, so you must set  isolation valve to open position. Be sure to follow the right steps for engine start.

 

The ground air cart is connected to the right side of the airplane and the right side of the bleed air system. Although it is connected to the right side of the air bleed system, engine number  1 must be started first, (boeing recommendation) for safety reasons because ground personnel and equipment are in the area of engine number 2.

The APU bleed air switch must be off. After starting number 1 and the engine is stabilized disconnect the external power equipment.   Then use crossbleed air to start number 2.

Follow the procedures for crossbleed air start.

 

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"On the A320, the No 1 engine powers the Green hydraulic system, which (in most MSNs) powers normal brakes and nosewheel steering. Both are quite useful things to have (especially if you are planning on carrying out a single-engine taxi) and so it makes sense to start #1 first in this case."

 

Not true: from the real A320 FCTM: "The engines are started in sequence, preferably engine 2 first, in order to pressurize

yellow hydraulic system, which supplies the parking brake accumulator." (page 103 a320/321 FCTM edition July, 8 2008).
In fact I've often flown aboard A319/A320 (Easyjet but this summer also Air Serbia) and I've almost always seen the right engine started first  apart once but was a Air Cart starting..
Ciao
Andrea Buono

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"On the A320, the No 1 engine powers the Green hydraulic system, which (in most MSNs) powers normal brakes and nosewheel steering. Both are quite useful things to have (especially if you are planning on carrying out a single-engine taxi) and so it makes sense to start #1 first in this case."

 

Not true: from the real A320 FCTM: "The engines are started in sequence, preferably engine 2 first, in order to pressurize

yellow hydraulic system, which supplies the parking brake accumulator." (page 103 a320/321 FCTM edition July, 8 2008).
In fact I've often flown aboard A319/A320 (Easyjet but this summer also Air Serbia) and I've almost always seen the right engine started first  apart once but was a Air Cart starting..
Ciao
Andrea Buono

 

It's strictly operator's decision. As I said earlier in the thread, the airline I worked for always started the  number one engine on the Airbus first.

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At American the first bunch of years I flew the 737 we started #1 first then #2. Then they started pushing single engine taxi out so they changed the procedure to start #2 first so we could use the #2 bleed for the right pack and APU for the left. Then we'd use the APU to start #1 while still having climate control from #2. If we do a start from an external air source we start #1 first.

 

As for the Airbus we start #1 first. I believe the reason is because the Green system is powered by #1 but has no electric pump. The Yellow system is powered by #2 but does have an electric pump. With only #1 running the Green system is powered by that engine driven pump and the Yellow electric pump can power it's system. If you did it the other way around you would have the PTU powering the Green system which makes a lot of noise in the cabin.

 

I've ridden on a handful of British Airways A320 family aircraft and they always started #1 first but I did see an A319 start #2 first one time. I also rode on a Virgin Atlantic/Aer Lingus A320 where they started #1 first.

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So to simplify, starting #2 first is recommended?

Either is acceptable. Just pay attention to the packs and the isolation valve.

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