What was found
DURING UPLATCH CHECK AFTER TAKE OFF, GEAR DOORS AND GEAR UNSAFE LIGHTS CAME ON. CREW PERFORMED UNSATISFACTORY UPLATCH CHECK (WARNING LIGHTS ON) CHECK WAS STILL UNSATISFACTORY. CREW RETURNED AIRCRAFT AND LANDED WITHOUT INCIDENT. AN INVESTIGATION IS ON GOING. AS MORE INFORMATION BECOMES AVAILABLE IT WILL BE PROVIDED. MAINTENANCE TROUBLESHOT LANDING GEAR EXTENSION/ RETRACTION IN ENTIRETY. FOUND RT MAIN LANDING GEAR UPLATCH MECHANISM CORRODED. MAINTENANCE CLEANED THE MECHANISM ALONG WITH THE ATTACHING PARTS AND JACKED THE AIRCRAFT IAW ALL APPLICABLE MANUALS. OPERATIONAL CHECK GOOD AND AIRCRAFT WAS RETURNED TO SERVICE.