Airworthiness Directives; British Aerospace (Jetstream) Model 4101 Airplanes

This amendment supersedes an existing airworthiness directive (AD), applicable to certain British Aerospace (Jetstream) Model 4101 airplanes, that currently requires repetitive detailed visual inspections to detect cracks in the shear cleats of the roller guide structural support of the passenger door, and replacement of any cracked shear cleat with a new shear cleat. That AD also provides for an optional terminating modification that constitutes terminating action for the repetitive inspections. This amendment mandates accomplishment of the previously optional terminating modification. This amendment is prompted by reports indicating that fatigue cracking was detected in the roller guide shear cleats of the passenger door. The actions specified by this AD are intended to prevent such fatigue-related cracking, which could result in structural failure or loss of the passenger door, and consequent rapid depressurization of the airplane during flight.