70-09-01\tBOEING: Amdt. 39-976. Applies to Model 737 series airplanes. \n\n\tCompliance required within the next 250 hours time in service after the effective date of this ad, unless already accomplished. \n\n\tAs a result of FAA evaluations of the 737 electrical system sufficient cause has been found to prevent inadvertent operation of the battery switch located on the forward overhead panel. Inadvertent operation of the battery switch during some operating conditions could result in loss of the standby electrical system. To prevent inadvertent operation of the battery switch on the forward overhead panel on the subject 737 series airplanes, accomplish one of the following: \n\n\t\t(1)\tInstall a switch guard and light plate per the Boeing Service Bulletin No. 24- 1010 Revision (1) dated April 24, 1970, or later FAA approved revisions. \n\n\t\t(2)\tReplace the battery switch with a detent lock type switch, P/N MS 24659-23D or an equivalent MS type, provided the galley switch is a toggle type. \n\n\t\t(3)\tPerform an equivalent installation approved by the Chief, Aircraft Engineering Division, FAA, Western Region. \n\n\tThis amendment becomes effective April 23, 1970.