The FAA is proposing an airworthiness directive for MD Helicopters 369Ds, 369Es, 369Fs and 369FFs with specific serial-numbered tailboom assemblies. The AD was prompted by the discovery of short-edge margin conditions on two tailboom assemblies. The proposed actions are intended to detect a short-edge margin condition, to modify the tailboom by adding a longeron doubler over the area with the short-edge distance, and to prevent failure of the tailboom and subsequent loss of control of the helicopter. The FAA is taking comments until October 29.