Airworthiness Directives; Bombardier Model DHC-8-101, -102, -103, -106, -201, -202, -301, -311, and -315 Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to all Bombardier Model DHC-8-101, -102, -103, -106, -201, - 202, -301, -311, and -315 airplanes. This amendment requires a detailed inspection of the wing leading edge de-icer boots to determine if they comply with certain patch limits in the critical zone; and corrective action, if necessary. This action is necessary to prevent reduced aerodynamic smoothness of the wing leading edge de-icer boots and possible reduced stall margin, which could result in a significant increase in stall speeds, leading to a possible stall prior to activation of the stall warning. This action is intended to address the identified unsafe condition.