Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Bombardier Model DHC-8-100, -200, and -300 series airplanes. This proposal would require various modifications of the airstair (main passenger) door. This action is necessary to prevent failure of the airstair door to open after a landing, which could result in a blocked escape route during an emergency evacuation. This action is intended to address the identified unsafe condition.