Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Aerospatiale Model ATR42 and ATR72 series airplanes. This proposal would require modification of the alerting capability of the anti-icing advisory system to improve crew awareness of icing conditions, replacement of the median wing de-icing boots with extended de-icing boots, and installation of de-icing boots on the metallic wing leading edge. This proposal is prompted by issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by the proposed AD are intended to prevent degradation of lift and drag characteristics in prolonged severe icing exposure, which could result in loss of lift and consequent reduced controllability of the airplane.