Airworthiness Directives; Jetstream Model 4101 Airplanes

This amendment clarifies information in an existing airworthiness directive (AD), applicable to all Jetstream 4101 airplanes, that currently requires a review of maintenance records to determine the time-in-service of the bearings in the starter/generators of both engines. It also establishes a new time-in-service limit for the bearings, and requires replacement of the starter/generator unit with a serviceable unit, if necessary. The actions specified in that AD are intended to prevent failure of the bearings of the starter/ generator, which could cause severe vibrations and resultant in-flight shutdown of one or both engines. This amendment clarifies the requirements of the current AD by specifying the name of the manufacturer of the starter/generator units that are affected by the requirements of this AD.