777 Distribution of Hydraulics to Elevators
ibmpilot - I stand corrected, thanks for pointing out my error. I think I was confusing the 787 and 777. The 777 Left Hydraulic System does power two of the four elevator actuators. This distribution was chosen in conjunction with the hydraulic power for the two horizontal stabilizer control motors (one on C Hyd, the other on R Hyd). With is arrangement, loss of two hydraulic systems leaves you with either one elevator surface and the stabilizer active or no stabilizer, but both elevator surfaces powered.
Losing the L Hydraulic system will drop the system from the nominal two actuators on each elevator surface to only one active on each surface. In that situation horizontal stabilizer control is not compromised as it is not controlled by L Hyd.