N1 difference

[Driver170 42]

So i'm needing to change my packs ?

[G-CIVA 62]

Another reason not to buy FS2Crew then.

[pete_auau 1,159]

Another reason not to buy FS2Crew then.

 

And  what has fs2crew got  to do with the issue?

[Driver170 42]

Another reason not to buy FS2Crew then.

 

and why is that steve?

[Jetstream96 20]

Ha, thanks! Couldn't turn the opportunity down.

 

 

 

Is a packs OFF takeoff even approved? Never seen that procedure in the FCOM?

Packs off takeoffs are used when the plane is heavy and OAT is very high. Not sure whether it's used often on 737NG, but it can be useful for wide-body A/C at OMDB during summer.

 

The procedure can be found in FCOM, see supplementary procedure -> air sys. -> No engine bleed TO and Landing.

 

Helios disaster ? Maybe thats why

You notice TOPCAT has AIR CON off or on option!? Is this effectively BLEEDS OFF

I guess that's why we have "engine bleeds - ON" "Packs - AUTO" in the after TO checklist.

[Spin737 102]

Helios disaster ? Maybe thats why

You notice TOPCAT has AIR CON off or on option!? Is this effectively BLEEDS OFF

 

 

Packs off takeoffs are used when the plane is heavy and OAT is very high. Not sure whether it's used often on 737NG, but it can be useful for wide-body A/C at OMDB during summer.

 

The procedure can be found in FCOM, see supplementary procedure -> air sys. -> No engine bleed TO and Landing.

 

I guess that's why we have "engine bleeds - ON" "Packs - AUTO" in the after TO checklist.

 

Vernon is correct. There is no PACKS OFF takeoff for the 737. There is BLEEDS OFF and UNPRESSURIZED, but in both cases the PACK switches are in AUTO. Even with the PACKS MELd, you have the switches ON.

[kevinh 409]

Helios disaster ? Maybe thats why

You notice TOPCAT has AIR CON off or on option!? Is this effectively BLEEDS OFF

Taking off with no pack running isn't going to cause an accident like that unless you continue to climb and don't turn them on after takeoff. The after takeoff checklist would ensure you had switched the packs on.

 

From a performance point of view Air Con OFF is the same as Bleeds OFF. if the APU is supplying a pack it isn't affecting engine performance.

[BlueStar 323]

can anyone explain the discrepancy between the 2 N1 engines

can anyone explain the discrepancy between the 2 N1 engines

Vernon,

 

No two engines are the same. Every engine will have a different N1/N2/EGT/FF at any given power setting/OAT/altitude. When the engine is installed it will go through a series of flight tests that will determine the engine operating parameters. The lower the N1 setting at maximum power output the stronger the engine.

 

Billy Bluestar

[Jetstream96 20]

Vernon is correct. There is no PACKS OFF takeoff for the 737. There is BLEEDS OFF and UNPRESSURIZED, but in both cases the PACK switches are in AUTO. Even with the PACKS MELd, you have the switches ON.

Oh indeed it's bleed off. My bad...

[Driver170 42]

From a performance point of view Air Con OFF is the same as Bleeds OFF. if the APU is supplying a pack it isn't affecting engine performance.

 

Thanks kevin so that option in TOPCAT is the same then.

 

 

Vernon,

 

No two engines are the same. Every engine will have a different N1/N2/EGT/FF at any given power setting/OAT/altitude. When the engine is installed it will go through a series of flight tests that will determine the engine operating parameters. The lower the N1 setting at maximum power output the stronger the engine.

 

Billy Bluestar

 

Yeh true, so its not a bug then with the NGX like someone explained? Need to look more into it

[Driver170 42]

If you check out the QRH PI 10.12 it talks about PACKS OFF correction? And nothing about engine bleeds

[Driver170 42]

Delete

[kevinh 409]

If you check out the QRH PI 10.12 it talks about PACKS OFF correction? And nothing about engine bleeds

I think the assumption there is that in flight it will be engines supplying the packs.

[Driver170 42]

Right, i'm not following! Its mentioning takeoff N1% adjustment for engine bleeds.

 

BLEED CONFIG - PACKS OFF at the bottom

[badderjet 181]

No two engines are the same.

 

Of course they are not, still the N1 is the same for both engines anytime. A/T controls N1. What you see IRL is simply a split in all other parameters, Other than that N1 is the same for both engines.