83-21-04: Outflow Valve Assemblies

83-21-04 BOEING: Amendment 39-4750. Applies to Boeing Model 767 and 757 series airplanes identified in the Boeing Service Bulletins listed in paragraph A., below. To prevent the loss of pressurization control due to failure of the cabin pressure control, accomplish the following within 750 hours time in service after the effective date of this AD, unless already accomplished: \n\n\tA.\tInspect and rework outflow valve actuators per Boeing Service Bulletins 757-21-9 or 767-21-13 dated May 23, 1983, and March 31, 1983, respectively as applicable, or later FAA approved revisions. \n\n\tB.\tRework the outflow valve assemblies per Boeing Service Bulletins 757-21-9 or 767- 21-15, Rev. 1, dated May 23, 1983, and March 31, 1983, respectively, as applicable, or later FAA approved revisions. \n\n\tC.\tAlternate means of compliance which provide an equivalent level of safety may be used when approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region. \n\n\tD.\tSpecial flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base for the accomplishment of inspections and/or modifications required by this AD. \n\n\tAll persons affected by this directive who have not already received the service bulletin(s) may obtain copies upon request from the Boeing Commercial Airplane Company, P.O. Box 3707, Seattle, Washington 98124. These documents may also be examined at the FAA, Northwest Mountain Region, 9010 East Marginal Way South, Seattle, Washington. \n\n\tThis amendment becomes effective November 28, 1983.