We propose to rescind an existing airworthiness directive (AD) that applies to certain The Boeing Company Model 737-600, -700, -700C, -800 and -900 series airplanes; and Model 757-200, -200PF, -200CB, and -300 series airplanes. The existing AD currently requires inspecting to determine if certain motor-operated shutoff valve actuators for the fuel tanks are installed, and related investigative and corrective actions if necessary. The existing AD also requires 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 series airplanes). We issued that 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. Since we issued that AD, we have received new data indicating that the existing AD addresses that safety concern, but also introduces a different unsafe condition.
Agency Contact: Rebel Nichols, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue SW., Renton, WA 98057-3356; phone: (425) 917- 6509; fax: (425) 917-6590; email: Rebel.Nichols@faa.gov.
This is a proposed regulation. Comments were due on October 11, 2012.