Summary
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 a determination that the protective polyurethane tapes applied to the upper surfaces of the aluminum and titanium floor structural members may not be trimmed properly, and on some places may overhang the profiles of the floor structural parts. Subsequent tests revealed that the overhanging pieces of tapes that are not bonded to the structure do not meet the flammability requirements and may allow fire propagation below the floor structure. This proposed AD would require an inspection of the polyurethane protective tapes installed on the floor structure for excess tape or incorrect tape installation, and corrective actions if necessary. We are proposing this AD to detect and correct overhanging pieces of protective polyurethane tapes, which are not bonded to the structure and do not meet the flammability requirements; this condition may allow fire propagation below the floor structure.