What was found
DESCENDING FROM 4000'O 3000' AND ABOUT 3800' AGL THRUST AT IDLE FLAPS AT 1, 210KTS IN FLCH , MASTER WARNING SOUNDED WITH CONFIG LIGHT AND "GEAR NOT DOWN " EICAS MESSAGE. LASTED ABOUT 1 SECONDAND THEN CEASED. FACT 18JUN19 12:12 BOS U T/S SYSTEM IAW FIM 31-51, FAULT TREE 811, TO STEP 34. REMOVED/REPLACED AND TESTED LANDING GEAR CONFIGURATION MODULE IAW MM 31-51-04/401, OPS CKS NORMAL. FACT 18JUN19 12:12 BOS T/S SYSTEM IAW FIM 31-51, FAULT TREE 811, TO STEP 34. REMOVED/REPLACED AND TESTED LANDING GEAR CONFIGURATION MODULE IAW MM 31-51-04/401, OPS CKS NORMAL.