Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Mitsubishi Model YS-11 and -11A series airplanes. This proposal would require the implementation of a corrosion prevention and control program. This proposal is prompted by incidents involving corrosion and fatigue cracking in transport category airplanes that are approaching or have exceeded their economic design goal; these incidents have jeopardized the airworthiness of the affected airplanes. The actions specified by the proposed AD are intended to prevent degradation of the structural capabilities of the affected airplanes due to problems associated with corrosion.