Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Bombardier Model CL-600-2B19 (Regional Jet Series 100 & 440) airplanes. This proposal would require repetitive inspections for cracking of the upper and lower web of the engine support beam at fuselage station 640, and repair if necessary. This proposal also would provide an optional terminating action for the repetitive inspections. This action is necessary to prevent failure of the engine support beam, a principal structural element, which could result in reduced structural integrity of the airplane. This action is intended to address the identified unsafe condition.