PPRuNe Forums - B737 Pneumatics

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Turin, your memory checks out:ok:. Mine on the other hand is stuffed full of useless 70's-80,s sitcom trivia. My -200 gen. fam. manual confirms the requirement to have the engine bleed valve open for engine start.

Quote:

Quote:
The high stage valve is closed during engine start.(737NG).
As I say, my reference is to the original arrangement with the -100/200 PW-JT8 powered 737.

There's a very old sketch here from a website discussing the 727 about 3/4 down the page. The bleed valve is not shown but clearly it would have to be open for engine start to allow air flow to the starter.

Hope this clarifies my point.

The high stage valve is closed during start(9th stage),and the Pressure regulator shutoff valve is ALSO closed when either the bleed is in OFF position or engine start valve is in OPEN position,and othe r reasons such as over pressure or temp...

I think you are talking about the CFM. I was referring to the JT8.

The bleed air supply duct junction to the starter on the CFM is upstream of the shutoff valve.

I'll wind my neck in now as we are going around in circles.