Original Message

The xfer pumps take the fuel from main to supply tanks.  In normal forward flight the aft pump will go dry first with the appropriate CAD msg followed by the fwd pump. They are then just sucking air so you turn them off.  Remember to always verify what switch before moving. If you left running I'm not sure anything would happen, but the rfm calls for turn off.  I'm not sure be check with the newest models 135 to see if that procedure is still valid.  Airbus may have changed due to too many inadvertent xfer pumps being turned off causing premature engine shut down