Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing airplanes, identified above. This proposed AD would require inspecting to determine if certain motor-operated shutoff valve actuators for the fuel tanks are installed, and related investigative and corrective actions if necessary. This proposed AD would also require revising the Airworthiness Limitations (AWLs) section of the Instructions for Continued Airworthiness to incorporate AWL No. 28-AWL- 21, No. 28-AWL-22, and No. 28-AWL-24 (for Model 737-600, -700, -700C, - 800 and -900 series airplanes), and No. 28-AWL-23, No. 28-AWL-24, and No. 28-AWL-25 (for Model 757-200, -200PF, -200CB, and -300). This proposed AD results from a design review of the fuel tank systems. We are proposing this AD to prevent electrical energy from lightning, hot shorts, or fault current from entering the fuel tank through the actuator shaft, which could result in fuel tank explosions and consequent loss of the airplane.