What was found
(CAN) DURING THE CLIMB THE CREW RECEIVED A LAVATORY SMOKE WARNING INDICATION. THE F/A NOTICED A LEATHER ODOR IN THE LAVATORY BUT NO EVIDENCE OF SMOKE OR FIRE. THE ACFT RETURNED TO THE DEPARTURE AIRPORT. ALL WIRING IN THE VICINITY OF THE LAVATORY WAS CHECKED WITH NFF. THE LAVATORY LIGHT BALLAST, PN BR9000-22 WAS REPLACED. AS A PRECAUTION THE LAVATORY SMOKE DETECTOR WAS ALSO REPLACED, PN PU90-421R3. A TEST FLIGHT WAS CARRIED OUT WITH NFF. THIS DEFECT REOCCURRED AS REPORTED ON SDR 20130308010. WE BELIEVE NOW THAT THE LIGHT BALLAST LISTED IN THIS ORIGINAL SDR 20130219003 WAS NOT THE ROOT CAUSE OF THE ISSUE EVEN THOUGH IT WAS REPLACED AT THE TIME. WHEN THE DEFECT REOCCURRED, MORE IN DEPTH TROUBLESHOOTING REVEALED THAT THE ORDNANCE SIGN WAS THE CAUSE OF THE ODOR AS DETAILED IN SDR 20130308010. THERE HAS BEEN NO REOCCURRENCE SINCE THAT SDR WAS FILED.