Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede Airworthiness Directive (AD) 2013-23- 03, which applies to certain The Boeing Company Model 747-100, 747- 100B, 747-100B SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-400F, and 747SR series airplanes. AD 2013-23-03 currently requires doing a detailed inspection of certain attach fittings for a cylindrical defect and replacing if necessary. Since we issued AD 2013- 23-03, we received a report that a machining defect was also found on some of the actuator assemblies inspected during manufacture. This defect could lead to fatigue cracking and subsequent fracture. For certain airplanes, this proposed AD would mandate new inspections of the inboard actuator attach fittings for machining defects, and overhaul or replacement, if necessary. This proposed AD would also limit the compliance time for doing the replacement for certain other airplanes. We are proposing this AD to detect and correct defective inboard actuator attach fittings which, combined with loss of the outboard actuator load path, could result in uncontrolled retraction of the outboard flap, damage to flight control systems, and consequent reduced controllability of the airplane.