90-11-11 BOEING: Amendment 39-6610. Docket No. 90-NM-70-AD. \n\n\tApplicability: Model 747-400 series airplanes, listed in Boeing Alert Service Bulletin 747-35A2067, dated March 15, 1990, certificated in any category. \n\n\tCompliance: Required within the next 500 hours time-in-service after the effective date of this AD, unless previously accomplished. \n\n\tTo prevent disablement of the passenger oxygen system, accomplish the following: \n\n\tA.\tRemove and replace the passenger oxygen/yaw damper module in accordance with Boeing Alert Service Bulletin 747-35A2067, dated March 15, 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, FAA, Northwest Mountain Region. \n\n\tNOTE: The request should be forwarded through an FAA Principal Maintenance Inspector (PMI), who will either concur or comment, and then send it to the Manager,Seattle Aircraft Certification Office. \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 information from the manufacturer may obtain copies upon request to Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124. This information may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 17900 Pacific Highway South, Seattle, Washington, or Seattle Aircraft Certification Office, 9010 East Marginal Way South, Seattle, Washington. \n\n\tThis amendment (39-6610, AD 90-11-11) becomes effective on June 11, 1990.