What was found
ON DESCENT THROUGH APPROX 8,000 FT, GEAR WARNING HORN SOUNDED. GEAR LIGHT SHOWED L GEAR (RED), N GEAR (RED), R GEAR (RED) AND GREEN. THIS OCCURED DURING APU START-UP. OHMED OUT SWITCH, NO DEFECTS WERE NOTED. OHMED OUT LT & RT MAIN GEAR LEG DOWNLOCK, WOW & DOOR SWITCHES IAW WPC 32-60-10-04/32-60-30-03. FOUND RT MAIN LEG DOWNLOCK SWITCH DESIGNATION "JM" DEFECTIVE. REMOVED DEFECTIVE DOWNLOCK SWITCH AND INSTALLED NEW CUSTOMER SUPPLIED SWITCH IAW MM 32-60-00. ACCOMPLISHED FUNCTIONAL CHECKS OF GEAR IAW 29-10-00 NO DEFECTS WERE NOTED.