AD 99-22-13 Amendment 39-11391

This amendment adopts a new airworthiness directive (AD), applicable to BHTC Model 407 helicopters, that requires visually inspecting the vertical fin (fin) for reduced skin thickness; repairing or replacing the fin, if necessary; and identifying fins that have been inspected or repaired. This amendment is prompted by a report of an inboard skin damaged during production. The actions specified by this AD are intended to detect fin assemblies with reduced skin thickness which, if not corrected, reduce the strength of the skin and could lead to failure of the fin and loss of control of the helicopter.