Summary
We are revising an earlier proposed airworthiness directive (AD) for certain Bombardier, Inc. Model BD-100-1A10 (Challenger 300) airplanes. That NPRM proposed an inspection to determine if a certain oxygen cylinder and regulator assembly (CRA) is installed and the replacement of affected oxygen CRAs. That NPRM was prompted by reports of deformation found at the neck of the pressure regulator body on the oxygen CRA. This action revises that NPRM by revising the compliance times. We are proposing this supplemental NPRM to prevent elongation of the pressure regulator neck, which could result in rupture of the oxygen cylinder, and in the case of cabin depressurization, oxygen not being available when required. Since these actions impose an additional burden over that proposed in the NPRM, we are reopening the comment period to allow the public the chance to comment on these proposed changes.