AD FAA-2008-0121

The FAA is adopting a new airworthiness directive (AD) for certain ATR Model ATR42-500 series airplanes. This AD requires removing metallized polyethylene terephtalate (MPET) insulation blankets installed on the left and the right sides of the airplane over frame 24 between stringers 5 and 14. This AD results from reports indicating that burnt spots were found on the MPET insulation blankets installed over frame 24. The actions specified by this AD are intended to ensure that MPET insulation blankets are removed over frame 24. Such MPET insulation blankets, if not removed, could propagate a small fire that is the result of an electrical arc and could lead to a much larger fire.