Hydraulic system nr.1 is used for the middle autopilot servo. so if this hydraulic system fails, .............

Question

...... does these servos not work anymore (because hydraulic system nr. 2 is used i.e. for the left autopilot servo)?

Answer 1

Do a elac ,sec check test and you will see the big picture

Answer 2

What airplane?

Many systems are config. different, and their may be a cross feed to allow the #2 system to provide for the servo tabs, but without specific aircraft, its impossible to tell.

Answer 3

That particular servo will fail, however there are redundant servos powered by the other hydraulic systems.  Each of them is capable of flying the aircraft itself.

Most airplanes are even designed to that ailerons on one side and spoilerons on the opposite side are powered by the same hydraulic system.  This means that you could theoretically lose at least two systems and still have control over your aircraft.