What was found
DURING C-CHECK MAINTENANCE, A PASSENGER OXYGEN CHECK WAS ACCOMPLISHED. THE LAVATORY OXYGEN MASK FAILED TO DEPLOY AT 14,440 FEET ALTITUDE. INVESTIGATION REVEALED THE ANEROID SWITCH HAD NOT BEEN INSTALLED. IT WAS DETERMINED THE ANEROID SWITCH AND ITS ASSOCIATED WIRING WHICH AUTOMATICALLY DEPLOY THE MASK HAD INADVERTENTLY BEEN REMOVED BY THE MODIFICATION THAT CHANGED THE AIRPLANE FROM A PASSENGER TO A FREIGHTER CONFIGURATION. THE ANEROID SWITCH AND ASSOCIATED WIRING WAS INSTALLED AND TESTED PER DAC DRAWING SP10350050, 'NEW', ENTITLED 'PASSENGER OXYGEN CONTROL'. (X)