90-26-04 BOEING: Amendment 39-6830. Docket No. 90-NM-135-AD. \n\n\tApplicability: Model 747 series airplanes, line numbers 1 through 39, certificated in any category. \n\n\tCompliance: Required within the next 4,500 hours time-in-service after the effective date of this AD, unless previously accomplished. \n\n\tTo prevent the loss of the airplane primary flight controls due to loss of hydraulic fluid from all four hydraulic systems, accomplish the following: \n\n\tA.\tModify the hydraulic lines in the elevator control system in accordance with Section III of the Accomplishment Instructions, Steps G through H, of Boeing Alert Service Bulletin 747-29A2063, Revision 5, dated June 7, 1990. \n\n\tB.\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\tC.\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 Airplane Group, P.O. Box 3707, Seattle, Washington 98124. These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington. \n\n\tThis amendment (39-6830, AD 90-26-04) becomes effective on January 15, 1991.