Systems Question about the CRJ 200

[dueguard1]

Can someone clarify what is the difference between a cross bleed Start and a normal engine start on the CRJ 200, and which one is used more often? When would you have to use the cross bleed start?....... I'm just trying to understand this stuff better?

What exactly is 10th stage bleed air, and 14thstage bleed air?

 

[paulsalem]

Can someone clarify what is the difference between a cross bleed Start and a normal engine start on the CRJ 200, and which one is used more often? When would you have to use the cross bleed start?....... I'm just trying to understand this stuff better?

What exactly is 10th stage bleed air, and 14thstage bleed air?

Bleed air in jet turbines is compressed air taken from within the engine, after the compressor stage(s) and before the fuel is injected in the burners. The stages are just different compressors.

10th stage air is used for engine start, and Air Conditioning (including heating) as well as pressurization.

14th Stage is used for the engine cowl and wing anti-ice (no anti-ice on the tail) and to operate the thrust reversers.

Normal engine start uses the APU to provide bleed air to engage the Air Turbine starter. Basically you need air to start the engine turning. There is no electric starter like there is on a piston, or like on a King Air. If the APU is inoperative then you must use high pressure external air (start cart) to start on of the engines (left in the 200). You then increase power on the left engine (to compress more air) and use the 10th stage bleed air off of it, to start the right engine.

I Hope that helps. I just got out of CRJ school, so hopefully this is correct.

 

[mynameisjim]

In more simple terms, a normal start uses air provided by the APU. A cross bleed start uses air provided by the other (already running) engine.

 

[Turkey Shoot]

Must be a Pinnacle interview.......

 

[snap145]

it should be clarified as well...that during a cross bleed start....regardless of the aircraft..you are going to need a pretty high n1 rating on the running motor....checklists should specify....on the ERJ its 82%...not sure what it is on the CRJ...

 

[wmuflyguy]

it should be clarified as well...that during a cross bleed start....regardless of the aircraft..you are going to need a pretty high n1 rating on the running motor....checklists should specify....on the ERJ its 82%...not sure what it is on the CRJ...

60 PSI

 

[nethan]

If the APU is inoperative then you must use high pressure external air (start cart) to start on of the engines (left in the 200). You then increase power on the left engine (to compress more air) and use the 10th stage bleed air off of it, to start the right engine.

We start the right engine off a ground air start. Then, if they let us (rare) start the left engine. If not we push and then crossbleed start the right engine. I thought that was Bombardier's procedure, but I guess different places do it differently.

 

[DrewBlows]

it should be clarified as well...that during a cross bleed start....regardless of the aircraft..you are going to need a pretty high n1 rating on the running motor....checklists should specify....on the ERJ its 82%...not sure what it is on the CRJ...

Curiously, this is not true on the CR7. You only need 42 PSI in the bleed air system (there's only one), which is roughly equivalent to 75% n2. This is standard procedure to start engine #1 at Comair. We usually turn the APU off after starting #2 (except when I forget), and crossbleed start on the taxi.

The bleed air system is totally automatic, which leads to some interesting situations. If the cowl (or wing) anti-ice is on, the bleed air system will not draw air from the APU. Before cross-bleed starts became standard procedure, guys were doing them without even knowing it. They would turn the cowls on per the limitation and start the engine (thinking the APU would do it). I guess whether or not the engine would spool up depended on the thrust lever setting. I've done this by mistake, it's not a big deal, you just (usually) don't get a start.

As a side note we take off with the engine bleeds open (another automatic function). If we need a little extra performance we can leave the APU running (for bleed air), but I've never seen where this was necessary.

 

[paulsalem]

We start the right engine off a ground air start. Then, if they let us (rare) start the left engine. If not we push and then crossbleed start the right engine. I thought that was Bombardier's procedure, but I guess different places do it differently.

We talked about it in systems training, but I've yet to do a real one. Haven't gone to the sims yet. I guess you start the left b/c the right engine oil pressure gauge is AC powered. So if you were to start that first you'd have no oil pressure indication. So we start the left, cross bleed the right, and shut the left down to board the pax. Then cross bleed the left.

 

[Blucher]

We talked about it in systems training, but I've yet to do a real one. Haven't gone to the sims yet. I guess you start the left b/c the right engine oil pressure gauge is AC powered. So if you were to start that first you'd have no oil pressure indication. So we start the left, cross bleed the right, and shut the left down to board the pax. Then cross bleed the left.

If you've got an AC power cart it makes it a whole lot easier.

-Blucher

 

[paulsalem]

If you've got an AC power cart it makes it a whole lot easier.

-Blucher

Yes it would

 

[n32jk]

Must be a Pinnacle interview.......

Nope Pinnacle wouldn't ask tough questions like that

 

[Dirty Sanchez]

If you've got an AC power cart it makes it a whole lot easier.

-Blucher

Why?

Is it that much more difficult to start #2 with the jetbridge attached and the main door open?

 

[ReportCanoa]

This is all wrong. Y'all need to study.

 

[nethan]

I didn't even know that the oil pressure gauge was AC powered. That's a bit more indepth then the CBTs went I think. I don't think I've ever done a battery only start We've always had an APU with the LCV valve stuck or no APU but a ground power cart. The only reason I can think of for going with the right engine first (other then you can't really taxi on just the left engine unless you put the b pumps on) is that the ground air connection is right there and some line guys don't want to be standing under a running engine when they pull the air. Granted, it doesn't stop them from starting to unload bags while the engine is still spinning.

 

[ReportCanoa]

(other then you can't really taxi on just the left engine unless you put the b pumps on)

Aw, come on. I would amend that to say- you shouldn't taxy with the left engine only and single generator with the flaps up.

 

[Popeye0537]

it should be clarified as well...that during a cross bleed start....regardless of the aircraft..you are going to need a pretty high n1 rating on the running motor....checklists should specify....on the ERJ its 82%...not sure what it is on the CRJ...

That would be N2 snap....... 82% N1 is T/O power

 

[atrdriver]

I didn't even know that the oil pressure gauge was AC powered. That's a bit more indepth then the CBTs went I think. I don't think I've ever done a battery only start We've always had an APU with the LCV valve stuck or no APU but a ground power cart. The only reason I can think of for going with the right engine first (other then you can't really taxi on just the left engine unless you put the b pumps on) is that the ground air connection is right there and some line guys don't want to be standing under a running engine when they pull the air. Granted, it doesn't stop them from starting to unload bags while the engine is still spinning.

On the 200 the #1 oil pressure gauge is DC powered, so if you have to do a battery start with external air you start #1 first. Supposedly Bombardier has since said that it doesn't matter because it takes so long for the low oil pressure indication to show up that you have a gen online anyway.

 

[Blucher]

Why?

Is it that much more difficult to start #2 with the jetbridge attached and the main door open?

Alright Dirty Sanchez,

I admit it....I don't know what you're talking about. Please explain.

-Blucher

 

[ERfly]

I fly the ERJ, but is it common to do a battery start and just leave the engine running during boarding at some carriers? I've always thought that if they APU is MEL'd (or any part of it). The aircraft stays on ground power until boarding is done and the doors are closed. Then the engine is started with a huffer cart or bottle at the gate, power disconnected then the aircraft pushed back with an engine running.

At XJT, we start #2 on the gate with an MEL'd APU only because the nosewheel steering is on the #1 Hyd. system and we don't want to risk it engaging during pushback.