Summary
This document revises an earlier proposed airworthiness directive (AD), applicable to all British Aerospace (Jetstream) Model 4101 airplanes. That proposal would have required repetitively inspecting to detect damage of the structure associated with the engine nacelle fairing attached to the wing flaps, and repair of any damage found; drilling a new drain hole in each engine nacelle fairing; and applying a sealant to the gap between the wing flap and engine nacelle fairing. That proposal was prompted by reports of fatigue cracks found in the structure that attaches the engine nacelle fairing to the wing flaps. This new action revises the proposed AD by adding requirements to perform corrective actions for discrepancies and accomplish a modification that would terminate the repetitive inspections. This new action also would limit the applicability. The actions specified by this new proposed AD are intended to prevent such fatigue cracking, which could result in the partial or complete separation of the fairing from the wing flap, and consequent additional structural damage to the airframe and/or reduced controllability of the airplane.