Airworthiness Directives; Bombardier Model CL-600-2B19 (Regional Jet Series 100 & 440) Airplanes

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Bombardier Model CL-600-2B19 (Regional Jet series 100 & 440) airplanes. This action requires revising the airworthiness limitations section of the Instructions for Continued Airworthiness by incorporating new structural inspection intervals for the pressure floor skin of the center fuselage at fuselage stations 460 and 513; repair if necessary; and submission of inspection findings to the airplane manufacturer. This action is necessary to detect and correct in a timely manner fatigue cracks of the pressure floor skin of the center fuselage at fuselage stations 460 and 513, which could result in failure of the pressure floor skin and consequent rapid decompression of the airplane during flight. This action is intended to address the identified unsafe condition.