Very interesting question...
And I did not know that some B737s did not come with Recirculation Fans.
I know that the B737-3/5/6/700s have ONE and the B737-4/8/900 have two.
And regarding the Forward Outflow Valves, they only discharge air overboard if the Recirc Fans are off and the Main Outlfow Valve is open. It is the Flow Ctrl Valve that works off of Differential pressure on the Classics.
Last edited by B73567AMT; 18th April 2004 at 04:57.