Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede an existing airworthiness directive (AD) that applies to certain The Boeing Company Model 737-600, -700, - 700C, -800, and -900 series airplanes. The existing AD currently requires replacing the drain tube assemblies and support clamps on the aft fairing of the engine struts. Since we issued that AD, we received an additional report of a broken drain tube assembly on the aft fairing of the left engine strut at the clamp support location under the aft fairing compartment, inside the heat shield cavity of the aft fairing. There have also been reports of tube wear at the clamp location on additional airplanes. This proposed AD would require replacing the drain tube assembly of the left and right engine strut aft fairings with a new one which includes an integral support clamp made of nickel alloy 625. This proposed AD would also add airplanes to the applicability. We are proposing this AD to prevent failure of the drain tube assemblies and clamps on the aft fairings of the engine struts. Such failure could allow leaked flammable fluids in the drain systems to discharge onto the heat shields of the aft fairings of the engine struts, which could result in an undetected and uncontrollable fire.