Airworthiness Directives; Pratt & Whitney JT9D-3A, -7, -7A, -7F, -7H, -7AH, and -7J Turbofan Engines

摘要

The FAA is revising an existing airworthiness directive (AD) for Pratt & Whitney (PW) JT9D-3A, -7, -7A, -7F, -7H, -7AH, and -7J turbofan engines, with gearbox pressure tube, part number (P/N) 697896, and No. 4 bearing front pressure manifold, P/N 670663, installed. That AD currently requires a one-time visual inspection of the gearbox pressure tube and No. 4 bearing front pressure manifold and the attaching clamp assemblies for correct positioning and for wear and damage, and replacement if necessary. This ad requires the same actions. This AD results from the need to correct errors in depicted clamping to ensure that AD compliance can be achieved, and to relax the level of maintenance required, as an optional method, when inspecting the affected tubing for dents. We are issuing this AD to prevent engine fires caused by failed gearbox pressure tubes or failed No. 4 bearing front pressure manifolds.