Airworthiness Directives; Boeing Model 707-300B, -300C, and -400 Series Airplanes

The FAA is adopting a new airworthiness directive (AD) for all Boeing Model 707-300B, -300C, and -400 series airplanes. This AD requires repetitive inspections to detect cracked or broken hinge fitting assemblies of the inboard leading edge slats, and corrective action if necessary. This AD also provides as an option a preventive modification, which defers the repetitive inspections. In addition, this AD provides an option of replacing all hinge fitting assemblies with new, improved parts, which terminates the repetitive inspection requirements. This AD is prompted by results of a review to identify and implement procedures to ensure the continued structural airworthiness of aging transport category airplanes. We are issuing this AD to detect and correct fatigue cracking of the hinge fitting assembly of the inboard leading edge slats, which could result in reduced structural integrity of the slat system. This condition could result in loss of the inboard leading edge slat and could cause the flightcrew to lose control of the airplane.