Airworthiness Directives; Bombardier Model DHC-8-400 Series Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain Bombardier Model DHC-8-400 series airplanes. This AD requires an inspection of the laminated shims for cracks, damage, or extrusion between the forward attachment fittings of the horizontal stabilizer and the top rib of the vertical stabilizer; a torque check of the attachment bolts in the attachment fittings of the front, middle, and rear spars; and corrective actions if necessary. This AD results from a report indicating that delaminated shims extruded from the interface between the forward attaching fittings of the horizontal stabilizer and the top rib of the vertical stabilizer, and that inadequate torque values of some bolts were found. We are issuing this AD to prevent reduced structural integrity of the horizontal stabilizer, and consequent loss of controllability of the airplane.