Airworthiness Directives; Gulfstream Aerospace Corporation Airplanes

We are adopting a new airworthiness directive (AD) for all Gulfstream Aerospace Corporation Model G-1159, G-1159A, G-1159B, G-IV, and GV airplanes; and certain Model GIV-X and GV-SP airplanes. This AD requires a one-time replacement of the actuator end cap fitting of the main landing gear (MLG) door, and revision of the maintenance or inspection program to establish the life limit of the end cap fitting. This AD was prompted by a report of the failure of the right MLG to extend due to fatigue cracking of the end cap fitting. We are issuing this AD to prevent such cracking, which could result in depletion of the combined (left) and utility hydraulic system fluid and the nitrogen emergency blowdown system, failure of the combined (left) hydraulic system (all phases) to provide adequate hydraulic pressure, and failure of the MLG to extend when commanded.