Brasilia Engine Start
- Thread starter Tmoney22
- Start date
turbojet28
Well-Known Member
I am not qualified to give an official response, but it perhaps could be that the engine actually is started, but the exhaust being used for things like what an APU (auxiallry power unit) does (like electronics, air conditioning, etc.) instead of turning the prop. Just a guess though!
mtsu_av8er
Well-Known Member
It's not the exhaust that's used for those things, it's actually compressed air - called "bleed air" - taken from the last portion of the compressor section (in most cases).
turbojet28
Well-Known Member
Thanks Lloyd. I meant something along those lines!
RiddlePilot
New Member
Don't they usually alternate the start between left/right based on the flight number?
kellwolf
Piece of Trash
On the 737, the number two runs the a/c and I THINK maybe some of the pressurization systems. SWA just changed the procedures to start #2 first ALL the time. As far a the Brasilia goes, I don't know. It could be the same thing. Before the procedure change, the engine start sequence was left to the discretion of the captain.
RiddlePilot
New Member
Modern jets really don't work like that though. There's not one engine that controls the air conditioning, and one that does not. The engines provide bleed air to the pneumatic system, which in turn provides air to the air conditioning packs. As long as the pneumatic system is provided enough pressure to run the packs, either engine can indirectly support the air conditioning.
But, here I am talking about systems that other folks on this board actually have experience with outside of a classroom. So, I digress.
But, here I am talking about systems that other folks on this board actually have experience with outside of a classroom. So, I digress.
Cheechako
Well-Known Member
Straight from the EMB SOP:
[ QUOTE ]
5) ENGINE STARTS
a) GENERAL
The Captain shall alternate first engine start between the left and
right. Should the flight crew determine that one engine has a
tendency to start hotter than the other engine, that engine may be
started last to extend engine and starter life.
[/ QUOTE ]
It's a simple cooling issue. That extra 2 minutes of cooling per quick turn can add up when an airplane does 12+ start cycles a day.
[ QUOTE ]
5) ENGINE STARTS
a) GENERAL
The Captain shall alternate first engine start between the left and
right. Should the flight crew determine that one engine has a
tendency to start hotter than the other engine, that engine may be
started last to extend engine and starter life.
[/ QUOTE ]
It's a simple cooling issue. That extra 2 minutes of cooling per quick turn can add up when an airplane does 12+ start cycles a day.
kellwolf
Piece of Trash
[ QUOTE ]
Modern jets really don't work like that though. There's not one engine that controls the air conditioning, and one that does not. The engines provide bleed air to the pneumatic system, which in turn provides air to the air conditioning packs. As long as the pneumatic system is provided enough pressure to run the packs, either engine can indirectly support the air conditioning.
[/ QUOTE ]
Depends on the jet I think. I know that the 737-300/700/500s run the a/c through the bleeds off the number two. I've been told this by several SWA captains, and the reason they start the number two first is "for passenger comfort and cooling." As far as taxi-ing in with the number one in Orlando, the APU can also run the packs. Our guys sometimes taxi in with only the number one since the cargo doors are on the number two side. This allows us to get in and start off-loading about 20-30 seconds faster. I think there might be a slight edge in fuel saving as well.
Modern jets really don't work like that though. There's not one engine that controls the air conditioning, and one that does not. The engines provide bleed air to the pneumatic system, which in turn provides air to the air conditioning packs. As long as the pneumatic system is provided enough pressure to run the packs, either engine can indirectly support the air conditioning.
[/ QUOTE ]
Depends on the jet I think. I know that the 737-300/700/500s run the a/c through the bleeds off the number two. I've been told this by several SWA captains, and the reason they start the number two first is "for passenger comfort and cooling." As far as taxi-ing in with the number one in Orlando, the APU can also run the packs. Our guys sometimes taxi in with only the number one since the cargo doors are on the number two side. This allows us to get in and start off-loading about 20-30 seconds faster. I think there might be a slight edge in fuel saving as well.
Mr_Creepy
Well-Known Member
Kell they are pulling your leg. The bleeds from either engine or the apu may be used to cool the plane. Even if the majority of #1 goes to the cockpit, it's still a common duct with a mixing plenum and plenty of cool air will go to the cabin.
Some airlines even allow you to MEL a pack and fly with just one.
Some airlines even allow you to MEL a pack and fly with just one.
Bandit_Driver
Gold Member
Can't comment on the EMB. But in the Saab 340 we always start #2 first. This is done for a couple of reasons. 1st it is away from the passenger door so it can be running while boarding pax. 2nd it supplies bleed air direclty to the right pack which sends 1/3 of the A/C to the cockpit and 2/3 to the cabin without having to xfer the bleed air. You usually won't see #1 started first unless the crew had a problem starting number #2. Then they will board and start 1 then try 2 again. Done for cooling and company policy reasons.
