Summary
We propose to adopt a new airworthiness directive (AD) for Bell Helicopter Textron Canada (BHTC) Model 407 helicopters. This proposed AD would require inspecting the aft fuselage upper skin (upper skin) for a crack and the upper left longeron assembly (longeron assembly) for a crack, corrosion, or defect. This AD would require replacing or repairing a part or section, depending on the inspection's outcome. This proposed AD is prompted by reports of cracks in the upper left-hand longeron. The proposed actions are intended to prevent failure of the longeron assembly or the upper skin, which could lead to a structural failure and loss of helicopter control.