Airworthiness Directives; McDonnell Douglas Model DC-9-10, -20, -30, -40, and -50 Series Airplanes and C-9 (Military) Airplanes

Résumé

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-9-10, -20, -30, -40, and -50 series airplanes and C-9 (military) airplanes. This proposal would require, among other actions, various inspections to detect cracks of the cockpit enclosure window sill, and follow-on and corrective actions, as applicable. This action is necessary to prevent fatigue cracking of the internal doublers and frame structure of the fuselage skin of the cockpit enclosure window sill. This action is intended to address the identified unsafe condition.