B737 isolation valve
Got a question about the isolation valve in the B737. I asked the question earlier but no response, still curious though.
Recently we switched to BOP. In the old procedure we always put the isolation valve in auto during engine start. According to boeing procedures we now put the isolation valve in open during engine start.
Okay, got no problems with that, in both cases the isolation valve is open anyways because the packs are off so it doesn't matter. But during a cross bleed start the FCOM now says to put the isolation valve in auto after #1 engine has been started(on an external source). and before you start engine #2. I can't figure out why? Anybody knows?
Thanks in advance