91-26-05 R1 BOEING: Amendment 39-8887. Docket 93-NM-64-AD. Revises AD 91-26-05, Amendment 39-8116. \n\n\tApplicability: Model 747-400 series airplanes, excluding airplanes having production line numbers 816, 839, and 961 and subsequent; certificated in any category. \n\n\tCompliance: Required as indicated, unless accomplished previously. \n\n\tNOTE 1: Paragraph (a) of this AD restates the requirements of paragraph (a) of AD 91-26-05, amendment 39-8116. As allowed by the phrase, "unless accomplished previously," if the requirements of AD 91-26-05 have been accomplished previously, paragraph (a) of this revised AD does not require the insertion of the Airplane Flight Manual (AFM) limitation to be repeated. \n\n\tTo prevent loss of all very high frequency (VHF) radio voice communication transmission capability, accomplish the following: \n\n\t(a)\tWithin 14 days after December 30, 1991 (the effective date of AD 91-26-05, amendment 39-8116): Add the following statement to the Limitations Section of the FAA- approved AFM. This may be accomplished by placing a copy of this AD in the AFM. \n\n\n\t"ELECTRONIC SYSTEMS \n\t\tVHF RADIO VOICE COMMUNICATIONS \n\n\t\tRight VHF radio (VHF R) communication system must be operational for dispatch." \n\n\t(b)\tReplacement of the currently-installed audio management unit (AMU) of the VHF radio communication system having Boeing part numbers S220U000-101, -102, or -104, (Hughes-Avicom part numbers 1167014-140, -141, or -142), with a modified AMU having Boeing part number S220U000-105 (Hughes part number 1167014-143), in accordance with Boeing Service Bulletin 747-23-2321, dated May 20, 1993, constitutes terminating action for the requirements of this AD. Following accomplishment of this replacement, the AFM limitation required by paragraph (a) of this AD may be removed. \n\n\t(c)\tAs of the effective date of this AD, no AMU having Boeing part numbers S220U000-101, -102, or -104, (Hughes-Avicom part numbers 1167014-140, -141, or -142), shall be installed on any airplane, unless the requirements of paragraph (a) of this AD have been accomplished. \n\n\t(d)\tAn alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Seattle ACO. \n\n\tNOTE 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. \n\n\t(e)\tSpecial flight permits may be issued in accordance with sections 21.197 and 21.199 Federal Aviation Regulations (14 CFR sections 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished. \n\n\t(f)\tThis amendment becomes effective on May 20, 1994.