90-17-19 BOEING: Amendment 39-6705. Docket No. 89-NM-120-AD. \n\n\tApplicability: Model 747 series airplanes, except the Model 747SP, certificated in any category. \n\n\tCompliance: Required as indicated, unless previously accomplished. \n\n\tTo prevent failure of the trailing edge flaps' carriage spindles, accomplish the following: \n\n\tA.\tIn accordance with the compliance schedule below, remove the aft link and thrust collars from the trailing edge flaps' carriage spindles and perform a detailed visual inspection of all exposed surfaces of the carriage spindles, including inner bore, and aft links to detect cracking and corrosion, in accordance with Boeing Service Bulletin 747-27-2280, Revision 3, dated November 30, 1989. \n\n\t\t1.\tPerform the initial inspection at the later of the following, unless previously accomplished within the last 11 months: \n\n\t\t\ta.\twithin 30 days after the effective date of this AD; or \n\n\t\t\tb.\tprior to the accumulation of 30,000 flight hours or 8 years on each new or previously overhauled flap carriage spindle, whichever occurs first. \n\n\t\t2.\tIf no cracking or corrosion is found, repeat the inspections required by paragraph A. of this AD, at intervals not to exceed 12 months until the carriage spindles are overhauled in accordance with paragraph B. of this AD. \n\n\t\t3.\tIf a cracked carriage spindle or aft link is found, prior to further flight, replace the part(s) in accordance with the service bulletin. \n\n\t\t4.\tIf corrosion is found on any part of the carriage spindle/aft link assembly, but not on the other assembly on the same flap perform a repetitive general visual inspection in accordance with the service bulletin at intervals not to exceed 2 months. Overhaul or replace corroded parts within 36 months after detection of the corrosion, but no later than 5 years after the effective date of this AD. \n\n\t\t5.\tIf corrosion is found on any part of both carriage spindle/aft link assemblies on the same flap, prior to further flight, overhaul or replace the part(s) in accordance with the service bulletin; or repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office, Transport Airplane Directorate. \n\n\tB.\tIn accordance with the schedule below, remove the carriage spindle and aft link, and overhaul in accordance with Boeing Service Bulletin 747-27-2280, Revision 3, dated November 30, 1989. \n\n\t\t1.\tPerform the initial overhaul at the latest of the following: \n\n\t\t\ta.\twithin 5 years after the effective date of this AD; or \n\n\t\t\tb.\tprior to the accumulation of 30,000 flight hours on any new or previously overhauled flap carriage spindle; or \n\n\t\t\tc.\tprior to the accumulation of 8 years on any new or previously overhauled flap carriage spindle. \n\n\t\t2.\tRepeat this overhaul thereafter at intervals not to exceed 30,000 flight hours or 8 years, whichever occurs first. \n\n\tC.\tAn alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. \n\n\tNOTE: The request should be submitted directly to the Manager, Seattle ACO, and a copy sent to the cognizant FAA Principal Inspector (PI). The PI will then forward comments or concurrence to the Seattle ACO. \n\n\tD.\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD. \n\n\tAll persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124. These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 17900 Pacific Highway South, Seattle, Washington, or Seattle Aircraft Certification Office, FAA, Northwest Mountain Region, 9010 East Marginal Way South, Seattle, Washington. \n\n\tAirworthiness Directive 90-17-19 supersedes AD 88-04-06 R1, Amendment 39-6164.\n \tThis amendment (39-6705, AD 90-17-19) becomes effective on September 21, 1990.