Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Jetstream Model 4101 airplanes, that currently requires repetitive purging of the hydraulic system and installation of a spoiler actuator that has been previously certified. That AD was prompted by a report of damage to the locking mechanisms on some pistons of the spoiler actuators. The actions specified by the AD are intended to prevent uncommanded extension of the lift spoiler in the event of loss of hydraulic pressure in the spoiler actuator. This action would establish an increased life limit for certain spoiler actuators, and provide an optional terminating action for the requirements of the AD. It would also limit the applicability of the rule to fewer airplanes.