Summary
This document proposes to adopt an airworthiness directive (AD) that would apply to Jetstream Aircraft Limited (JAL) HP137 Mk1, Jetstream series 200, and Jetstream Model 3101 airplanes. The proposed action would require repetitively inspecting the spigot housing plate for cracks at the wing/fuselage forward attachment sliding joint, replacing any cracked housing plate, repetitively inspecting the spigots and spigot posts for corrosion and installing improved spigots if corrosion is found, and eventually installing improved spigots if corrosion is not found. For certain affected airplanes, the proposed action would require repetitively inspecting the spigot bushes for migration gaps, replacing the bushes with modified bushes if gaps are found that exceed 0.5-inch, and eventually replacing the bushes with modified bushes if migration gaps are not found. Reports of bush migration gaps found on three of the affected airplanes and another report of corrosion and several cracks found on the spigot housing plate on a Jetstream Model 3101 airplane prompted the proposed action. The actions specified by the proposed AD are intended to prevent structural failure of the wing/fuselage area caused by a cracked or corroded spigot housing assembly.