Sec. 25.679 - Control system gust locks.
(a) There must be a device to prevent
damage to the control surfaces (including tabs), and to the control
system, from gusts striking the airplane while it is on the ground or
water. If the device, when engaged, prevents normal operation of the
control surfaces by the pilot, it must --
(1) Automatically disengage when the
pilot operates the primary flight controls in a normal manner; or
(2) Limit the operation of the airplane
so that the pilot receives unmistakable warning at the start of takeoff.
(b) The device must have means to
preclude the possibility of it becoming inadvertently engaged in flight.