68-17-05: Air System Center Section Duct

68-17-05 ROLLS-ROYCE: Amdt. 39-636 as amended by Amendment 39-1318 is further amended by Amendment 39-1474. Applies to Spey Engines Models 506-14, 510-14, 511-8, and 511-14. Compliance required as indicated, unless already accomplished. To prevent or contain a possible failure of the H.P. center section air duct and thereby prevent possible secondary powerplant damage, accomplish the following: (a) Within the next 300 hours time in service after the effective date of this AD, visually inspect (with the aid of a mirror as necessary) the high pressure air system center section duct, P/Ns EU.29670A and EU.63415A, particularly adjacent to welds, for cracks (discoloration of the cowling and engine adjacent to the duct may be indicative of a duct crack), and incorporate a stainless steel wire braid wrap around the high pressure air system center section duct, P/Ns EU.29670A and EU.63415A, in accordance with Rolls-Royce Service Bulletin No. SP. 75-86, dated November 20, 1967, or later ARB-approved or an equivalent approved by the Chief, Aircraft Certification Staff, FAA, Europe, Africa and Middle East Region. (b) At the next scheduled aircraft inspection when the engine is uncowled after compliance with paragraph (a), and thereafter at intervals not to exceed 1,000 hours' time in service from the last inspection, inspect (with the aid of a mirror as necessary) the exposed high pressure air system center section duct for signs of cracking and the stainless steel wire braid wrap for security, distortion, and discoloration. NOTE: Distortion or discoloration of the wire wrap may be indicative of a duct crack. (c) If defects are found during the inspections required by paragraphs (a) and (b), before further flight, replace, as required, the center section duct with a serviceable P/N EU.29670A or P/N EU.63415A duct and a new stainless steel wire braid wrap. (d) Upon the request of an operator, an FAA maintenance inspector, subject to priorapproval of the Chief, Aircraft Certification Staff, FAA, Europe, Africa and Middle East Region, may adjust the repetitive inspection interval specified in this AD to permit compliance at an established inspection period of the operator, if the request contains substantiating data to justify the increase for such operator. Amendment 39-636 became effective September 14, 1968. Amendment 39-1318 became effective October 12, 1971. This Amendment 39-1474 becomes effective 28 June 1972.