Summary
This document revises an earlier proposed airworthiness directive (AD), applicable to certain de Havilland Model DHC-8-100 and -300 series airplanes, that would have required inspections to detect corrosion on areas of the airplane structure where black film thermal insulation is used; repair, if necessary; and replacement of black insulation blankets with certain aluminized (silver) insulation. That proposal was prompted by reports of corrosion forming on areas of the airplane structure where the black film covers the thermal insulation blankets. This action would expand the inspection area, and would require replacement of the black film insulation in that area. This action also would expand the applicability of the proposed AD to include additional airplanes. The actions specified by this proposed AD are intended to prevent degradation of the structural capability of the airplane fuselage and sudden loss of cabin pressure due to corrosion of the airplane fuselage structure.