Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, and -900 Series Airplanes

The FAA is superseding an existing airworthiness directive (AD), which applies to all Boeing Model 737-600, -700, -700C, -800, and -900 series airplanes. That AD currently requires either determining exposure to runway deicing fluids containing potassium formate, or performing repetitive inspections of certain electrical connectors in the wheel well of the main landing gear (MLG) for corrosion, and follow-on actions. This new AD adds a new inspection requirement and related corrective actions. This AD is prompted by additional reports indicating that significant corrosion of the electrical connectors in the wheel well of the MLG has also been found on airplanes that land on runways treated with deicing fluids containing potassium acetate. We are issuing this AD to prevent corrosion and subsequent moisture ingress into the electrical connectors, which could result in an electrical short and consequent incorrect functioning of critical airplane systems essential to safe flight and landing of the airplane, including fire warning systems.