Summary
The FAA proposes to supersede an existing airworthiness directive (AD) that applies to certain McDonnell Douglas Model DC-9-10, -20, -30, -40 and -50 series airplanes, and Model DC-9-81 (MD-81), and DC-9-82 (MD-82) airplanes. That AD currently requires installing a water drain system for the slant pressure panels in the left and right wheel wells of the main landing gear (MLG). This proposed AD would also require inspecting the seal assemblies of the overwing emergency exit doors for defects and constant gap; replacing defective door seals; performing repetitive operational checks of the water drain system auto drain valve and corrective actions if necessary; and, for certain airplanes, modifying the insulation blankets on the slant pressure panels in the left and right MLG wheel wells. This proposed AD is prompted by reports of water runoff from the slant pressure panels in the left and right MLG wheel wells, which subsequently froze on the lateral control mixer and control cable assemblies. We are proposing this AD to prevent ice from forming on the lateral control mixer and control cable assemblies, which could reduce controllability of the airplane.