We are adopting a new airworthiness directive (AD) for the products listed above. This AD requires inspecting the wings for internal and external damage, repairing any damage, reinforcing the wings, installing operational limitation placards in the cockpit, and adding limitations to the airplane flight manual supplement. This AD was prompted by a review of installed Flint Aero, Inc. wing tip auxiliary fuel tanks, Supplemental Type Certificate (STC) SA5090NM. We are issuing this AD to detect and correct damage in the wings and to prevent overload failure of the wing due to the installation of the STC. Damage in the wing or overload failure of the wing could result in structural failure of the wing, which could result in loss of control.