What was found
UPON GEAR RETRACTION, RECEIVED A LT MAIN GEAR RED UNLOCK INDICATION WITH AN AMBER LT DOOR LIGHT. COMPLIED WITH ECAM EXTENDED GEAR & LANDED. WE DID HAVE A LOUD WIND NOISE WITH THE PROBLEM, PRETTY SURE DOOR WAS OPEN. DEBRIEFED CREW & VERIFIED THEY DID ATTEMPT GEAR RETRACTION IN BOTH SYS NR 1 & 2 WITH SAME RESULTS. LT MLG FAILED TO RETRACT. REMOVED LT MLG RETRACT ACT IAW MM 32-31-46-04AMM SMP. REPLACED LT MLG RETRACT ACTUATOR IAW A310-200. PERFORMED NORMAL LG RETRACTION & EXTENSION TEST, NO DEFECTS NOTED IAW MM 32-31-00-05.