Summary
This document revises an earlier proposed airworthiness directive (AD), applicable to certain McDonnell Douglas Model DC-9-80 and MD-90-30 series airplanes, and Model MD-88 airplanes, that would have required a determination to be made of whether, and at what locations, metallized polyethyleneteraphthalate (MPET) insulation blankets are installed, and replacement of MPET insulation blankets with new insulation blankets. That proposal was prompted by reports of in-flight and ground fires on certain airplanes manufactured with insulation blankets covered with MPET, which may contribute to the spread of a fire when ignition occurs from small ignition sources such as electrical arcing or sparking. This new action revises the proposed rule by expanding the applicability of the proposed rule to include additional airplanes. The actions specified by this new proposed AD are intended to ensure that insulation blankets constructed of MPET are removed from the fuselage. Such insulation blankets could propagate a small fire that is the result of an otherwise harmless electrical arc and could lead to a much larger fire.