Summary
We propose to adopt a new airworthiness directive (AD) for certain Bombardier, Inc. Model CL-600-2B19 (Regional Jet Series 100 & 440) airplanes. This proposed AD was prompted by reports that elevator power control unit (PCU) shear pins may fail prematurely. This proposed AD would require repetitive replacement of the elevator PCU shear pins. We are proposing this AD to prevent PCU failure of elevator PCU sheer pins. If all pins fail on one elevator, the elevator surface would become inoperative, which could reduce the controllability of the airplane and could result in a loss of redundancy for flutter prevention.