Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Aerospatiale Model ATR42-500 series airplanes, and Model ATR72-102, -202, -212, and -212A series airplanes. This proposal would require replacement of insulation blankets constructed of metallized polyethyleneteraphthalate (MPET) located from sections 11 through 16 of the fuselage with new insulation blankets constructed of Terul 18TM. This proposal is prompted by reports of in-flight and ground fires on certain airplanes manufactured with insulation blankets constructed of MPET, which may contribute to the spread of a fire when ignition occurs from small ignition sources such as electrical arcing or sparking. The action specified by the proposed AD is 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 toa much larger fire. This action is intended to address the identified unsafe condition.