Airworthiness Directives; Bombardier, Inc. Airplanes

We are adopting a new airworthiness directive (AD) for certain Bombardier, Inc. Model CL-600-2C10 (Regional Jet Series 700, 701, & 702); CL-600-2D15 (Regional Jet Series 705); CL-600-2D24 (Regional Jet Series 900); and CL-600-2E25 (Regional Jet Series 1000) airplanes. This AD was prompted by reports of deformation of the pressure regulator on the oxygen cylinder, which was attributed to batches of raw material that did not meet required tensile strength. This AD requires an inspection to determine if certain oxygen pressure regulators are installed, and replacement of oxygen cylinder and regulator assemblies (CRAs) containing pressure regulators that do not meet required material properties. We are issuing this AD 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 would not be available when required.