since the ground air doesn't feed both sides and you would have to use bleed air from No2 engine to start No1.

 

It can feed both sides. To minimize risks for ground personnel Boeing recommends to start engine 1, disconnect ground air and then do engine 2 crossbleed start.

"The isolation valve is the crossbleed valve. One and the same thing."

 

Thanks Kevin, so I was correct after all! LOL

 

Cheers

 

Neil

Whatever you call it, it has to be open.

.To summarize all the previous:

- 2 different Generators cannot be online on the same bus

- Each time you turn on APU or engines or ground personnel connect the ground power, there is no automatic switching to the last avaiable generator, all generators must be switched "online" before shutting down the previous source.

-Isolation valve has an AUTO logic wich prevent (most of the time) the needing of opening or closing it.

However is useful to know where the sources are connected to the system AND YOU CAN SEE HOW on the panel lines present between each switch.

The only exception is the ground connection.

Basically, the pneumatic system is divided in left and right, each engine will supply the onside system and the isolation valve will connect them in case you need pressure on the opposite side.

The APU (see the panel) is connected to the left system so it will supply pressure to the LEFT side, if the ISOL is open it will supply also the right side, if closed, only the left.

The ground air supply supplies air to the RIGHT side.

Each time you have APU or GROUND CART to start the opposite engine (right for APU, left for ground cart) you need to open the isolation valve. The AUTO logic will solve all problems as in AUTO position the isolation valve is open for ground starting (both Packs off).

To have correct procedures use the checklists that will normally tell you to OPEN isolation valve.

Believe this was covered in Tutorial 2...

Yes do you ever feel worthless Ryan? lol

 

Just to let you know, most of us DO appreciate your work and are better for it.

I have spent a couple of hours going through the Tutorial 2 documentation and getting the sequence written down in an easier to read way then printing the whole manual.

I now have document that takes me thought all the checks and setups from Cold and dark setup though to touchdown and securing the aircraft. It helps me get things in the right order. I think that for the APU and Engine start once I have run it a few times it will get into my memory – which is the component that fails most often!

 

Thanks for the help and feedback