Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Bombardier Model DHC-8-100, DHC-8-200, DHC-8-300, and DHC- 8-400 series airplanes. This proposed AD would require inspecting the left and right control column torque tube assemblies to determine the type of rivets installed and replacing incorrect or indeterminate type rivets with the correct type rivets. This proposed AD results from a report that incorrect rivets having lower than required strength were installed on the control column torque tube during production. We are proposing this AD to prevent shear failure of control column torque tube rivets, which could cause unexpected decoupling of the elevators and large unwanted deflection of the free elevator, and consequent reduced controllability of the airplane.