Summary
We propose to adopt 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 proposed 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 proposed AD would require 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 proposing 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.