Airworthiness Directives; Bombardier, Inc., Airplanes

We propose to adopt a new airworthiness directive (AD) for certain Bombardier, Inc., Model CL-600-2C10 (Regional Jet Series 700, 701 & 702) airplanes, Model CL-600-2D15 (Regional Jet Series 705) airplanes, Model CL-600-2D24 (Regional Jet Series 900) airplanes, and Model CL-600-2E25 (Regional Jet Series 1000) airplanes. This proposed AD was prompted by reports of a fractured main landing gear (MLG) orifice support tube (OST). This proposed AD would require replacing the MLG OST, and revising the maintenance or inspection program, as applicable, to incorporate new or more restrictive maintenance requirements and airworthiness limitations. We are proposing this AD to address the unsafe condition on these products.