AD 2003-24-12 Airworthiness Directives; Pratt & Whitney JT9D-3A, -7, -7A, -7F, -7H, -7AH, and -7J Turbofan Engines

This AD applies to 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. These engines are installed on, but not limited to, Boeing 747-100, -200B, -200C, and -200F airplanes.

You are responsible for having the actions required by this AD performed within 250 hours-in-service or at the next shop visit, whichever occurs first, after the effective date of this AD, unless the actions have already been done. One-Time Visual Inspection of Clamp Assemblies (f) Visually inspect the clamp assemblies, P/Ns ST1594-06, ST1594-08, and ST1594-10, that attach the gearbox pressure tube and the No. 4 bearing front pressure manifold to the engine. Replace clamp assemblies before further flight that are rejected by any of the following rejection criteria: (1) Droop in the No. 4 bearing front pressure manifold. (2) Cracks, wear, or distortion in clamp metal. (3) Clamp cushions that are worn, compacted, cracked, coming apart in chunks, deteriorated, or missing. A reddish powder found around the clamp is an indication of deterioration. One-Time Visual Inspection of Gearbox Pressure Tube and No. 4 Bearing Front Pressure Manifold (g) Clean any debris and oil from the outer surface of the gearbox pressure tube and No. 4 bearing front pressure manifold and visually inspect the tube and manifold. Repair or replace the affected tube or manifold before further flight if it is rejected by any of the following rejection criteria: (1) Nicks, chafing, scratches, and or pitting 0.003 inch or greater in depth. (2) Dents within 0.25 inch of the ferrules or will not permit free passage of a ball having a diameter slightly greater than 80% of the tube or manifold tubing inner diameter. (3) Corrosion that is unable to be removed by a light polishing. (4) Tube or manifold is leaking oil. Gearbox Pressure Tube, No. 4 Bearing Front Pressure Manifold, and Clamp Assembly Positioning (h) If the gearbox pressure tube, No. 4 bearing front pressure manifold, or clamp assemblies are not properly positioned, then correctly position them before further flight, as shown in the following Figure 1 of this AD. BILLING CODE 4910-13-P ER03DE03.007 BILLING CODE 4910-13-C (i) Information on general inspection of these parts can be found in the Boeing 747 Aircraft Maintenance Manual, section 72-00-00, and in PW Standard Practices Manual, P/N 585005. Reporting Requirements (j) Report within 30 calendar days of the inspection, the results that equal or exceed the reject criteria to: Engine Certification Office, FAA, Engine and Propeller Directorate, 12 New England Executive Park, Burlington, MA 01803-5299; telephone (781) 238-7189; fax (781) 238-7199. Reporting requirements have been approved by the Office of Management and Budget control number 2120-0056. Alternative Methods of

This AD is prompted by a report of a failed gearbox pressure tube that resulted in an engine fire. We are issuing this AD to prevent engine fires caused by failed gearbox pressure tubes or failed No. 4 bearing front pressure manifolds.