Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Jetstream Model 4101 airplanes. This proposal would require an inspection to determine the thickness of the intercostal that attaches the third crew member seat to the floor structure in the flight compartment, and replacement, if necessary. This proposal is prompted by a report from the manufacturer indicating that intercostals have been installed that are not of sufficient thickness (and consequent strength) to support the third crew member seat during emergency landing dynamic conditions. The actions specified by the proposed AD are intended to prevent the failure of this intercostal during an emergency landing, which could consequently result in injury to the flight crew.