From MIL-F- 8785C (November 1980):
The change in pitch control force required to maintain attitude and sideslip shall not exceed 20 lbs for at least 5 seconds following:
Complete or partial loss of any function of the augmentation system following a single failure.
Failure induced transient motions and trim changes either immediately after failure or upon subsequent transfer to alternate control modes.
Configuration changes required or recommended following failure.
From FAR part 23:
A maximum of 60 lbs stick force ( 75 lbs control wheel force) is allowed for temporary application.
A maximum of 10 lbs stick or control wheel force is allowed for prolonged application.
From FAR part 25:
A maximum of 75 lbs control wheel force is allowed for temporary application.
A maximum of 10 lbs control wheel force is allowed for prolonged application.
See Graphic