737CL DDPG 36-05-02 PRSOV
 

Recently had this come up. As per the approved MEL on fleet, the left engine bleed was inop. The O item specifies that with the LEFT bleed inop; Operations (O) 3.B.2: Operate the left pack using the right engine bleed, the right
pack OFF and isolation valve OPEN.

My question is, why run the left pack across the iso valve thru the manifold from the right engine bleed, instead of running the right pack from the right bleed valve with the iso valve closed? What am I missing in the system here? :ugh:

symetrical anti ice capability?

You cannot dispatch the aircraft into known/forecasted icing conditions with this MEL item.

My guess would be that isolation valve needs to be open in order to pressurize the L bleed duct - to have pressurization for hydraulic reservoir and water tank. I have no idea about the L vs. R pack, other than it might be to prioritize air for cockpit instead of the cabin.

Wing anti-ice is not available in this condition, hence prohibition of flight into known icing conditions.
As for pressurising the left duct, this is the best (and correct) answer...

I'm in agreement with FlyingStone, left pack although identical to the right pack in design & function, only the left pack supplies flight deck air.