Packs are a good one, electrically controlled pneumatically operated, if the electrical operation fails they run automatically therefore fail-safe.
Ie packs selected off (electrical signal) engines running bleed pressurized and turn all the generators off packs will run.
Electrically controlled or signalled but the muscle is hydraulic or pneumatic.
So without a electrical signal the muscle is designed to usually fail open or fail closed or fail on fail off.
And with electrics but no muscle (hyd/pneumatic failure) nothing moves.