Bleed Vlaves on or off during takeoff

[jkieffer1957]

I've noticed a couple of youtube videos where the pilot is turning off the bleed valves prior to takeoff and then turning them back on. Is this an established procedure? And are there any benefits to doing this? Just Curious, I follow the provided checklist for setting up for takeoff.

 

Regards

Jim Kieffer

Greenville NC

[Goran_M]

Correct me if I'm wrong, but what I think you're seeing is people RESETTING the bleed air.  The reset switch is spring loaded and will snap back to center when you let go of the mouse button.  

[Nano]

Turning the bleeds off prior to take-off will give you slightly better takeoff/climb performance.  Most jet AFMs will have takeoff calculations for bleeds ON and bleeds OFF.  Where this comes in handy is short runway/high pressure altitude situations.  Many small jets depart mountainous airports; i.e. Vail, Aspen, with the bleeds off.  Especially if they are at max weight for the conditions.

 

Other than that, it is not normal procedure to turn bleeds OFF for takeoff.

[jkieffer1957]

Correct me if I'm wrong, but what I think you're seeing is people RESETTING the bleed air.  The reset switch is spring loaded and will snap back to center when you let go of the mouse button.  

No he's definitely cutting off the Bleed controls, because he even talks about turning them back on when he is in climb out.

 

 

Turning the bleeds off prior to take-off will give you slightly better takeoff/climb performance.  Most jet AFMs will have takeoff calculations for bleeds ON and bleeds OFF.  Where this comes in handy is short runway/high pressure altitude situations.  Many small jets depart mountainous airports; i.e. Vail, Aspen, with the bleeds off.  Especially if they are at max weight for the conditions.

 

Other than that, it is not normal procedure to turn bleeds OFF for takeoff.

That's what I thought, so I have been following the procedures correctly.

 

I greatly appreciate your responses to my questions. It helps a great deal.

 

Regards

Jim Kieffer

Greenville NC