Summary
We propose to adopt a new airworthiness directive (AD) for MD Helicopters, Inc. (MDHI) Model 369D, 369E, 369F, and 369FF helicopters with certain serial-numbered tailboom assemblies. This proposed AD is 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.