68-25-02\tBOEING: Amendment 39-689. Applies to all Model B737 Series Airplanes. \n\tCompliance required as indicated: \n\t(1)\tPrior to next flight, unless already accomplished, use a screwdriver to assure that mounting screws holding M360 printed circuit card are tight. \n\t(2)\tIf screws holding M360 printed circuit card are not tight, replace NAS 1068 nutplates with self-locking nuts NAS 679A08W. \n\t(3)\tWithin the next 50 hours' time in service after the effective date of this AD, unless previously accomplished, replace NAS 1068 nutplates with self-locking nuts NAS 679A08W and make certain that receptacle D1136 is secure. \n\t(4)\tWithin the next 400 hours' time in service after the effective date of this AD, unless already accomplished, modify the interphone power circuits to separate the captain's and first officer's power sources and provide dual power sources to each interphone system in accordance with the section entitled "II. Accomplishment Instructions", of Boeing Service Bulletin 24-1009, Revision 1, November 8, 1968, or later FAA approved revision thereof, or an equivalent modification approved by the Chief, Aircraft Engineering Division, FAA Western Region. \n\tThis amendment becomes effective, insofar as compliance requirements (1), (2) and (3) are concerned, upon publication in the FEDERAL REGISTER for all persons except those to whom these requirements were made effective immediately by telegram dated November 1, 1968. \n\tThis amendment becomes effective, insofar as compliance requirement (4) is concerned, for all persons on December 10, 1968.