83-19-06 BOEING: Amendment 39-4736. Applies to Boeing Model 767 series airplanes equipped with Pratt and Whitney JT9D-7R4D engines certificated in all categories. In order to minimize the possibility of engine stall conditions during low power (idle) descent accomplish the following, unless already accomplished: \n\n\tA.\tWithin 30 days after the effective date of this AD, perform the airplane circuit modifications detailed in Boeing Alert Service Bulletin 767-73A7, dated September 2, 1983, or later FAA approved revisions. \n\n\tB.\tWithin 120 days after the effective date of this AD install Package B type hydromechanical fuel controls in accordance with Pratt & Whitney Aircraft Service Bulletin JT9D-7R4-73-4, dated May 3, 1983, or later FAA approved revisions. \n\n\tNOTE: Engine idle speeds associated with these modifications are not intended to replace or eliminate the requirement for proper observance of existing engine anti-ice limitations when operating in icing conditions, including selection of engine anti-ice "ON" and establishment of correct fan speeds prior to entering icing conditions. \n\n\tC.\tAlternate means of compliance with this AD 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.\tAirplanes may be flown in accordance with FAR 21.197 to a maintenance base to accomplish the above. \n\n\tThis amendment becomes effective October 11, 1983.