In essence SFCC1 looks after the left wing and SFFC2 looks after the right wing under normal ops and they act as a back-up for each other. On the left wing (for SLATS), SFCC1+BL HYD is the "primary" with SFCC2+GN HYD as backup. On the right it's SFCC2+GN HYD as "primary" backed up with SFCC1+BL.
It's a similar arrangement for FLAPS - left is SFCC1+GN backed up with SFCC2+YL and right wing is SFCC2+YL backed up with SFCC1+GN.
Under normal ops the hydraulic load is spread but you can see that the loss of SFCC2 in EEC results in one HYD system (BL) driving the SLATS and one (GN) for flaps - hence they run slow. It's a similar thing if you lose one HYD system - the back-up system is now working twice as hard and hence they're slow.
Last edited by A4; 14th October 2013 at 14:11.