Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Bombardier Model DHC-8-102, -103, -106, -201, -202, -301, -311, and -315 series airplanes. This proposal would require modifying the oxygen flow control valve. This action is necessary to ensure that proper oxygen flow will be available to passengers when needed. This action is intended to address the identified unsafe condition.