Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Bombardier Model DHC-8-301, -311, and -315 airplanes. This proposal would require determining the modification number of the angle of attack (AOA) sensor vanes; testing the movement of the affected vanes to evaluate sticking against both the upper and the lower vane travel end stops; and corrective action, if necessary. This action is necessary to prevent an incorrect AOA indication to the stall warning system in flight, which could result in an inadvertent stall and consequent loss of control of the airplane. This action is intended to address the identified unsafe condition.