What was found
WHEN LANDING GEAR WAS SELECTED UP, AFTER TAKEOFF, NOSE & RT MAIN GEAR INDICATIONS WERE NORMAL, BUT LT MAIN SHOWED UNLOCKED & DOOR. CYCLED GEAR WITH SAME RESULT. LG RETRACTION UNAVAILABLE, WAS ANNUNCIATED ALONG WITH GREEN SYS AIR PRESS LOW. WHEN LG WAS SELECTED TO DOWN, NORMAL 3 GREEN LIGHTS ILLUMINATED. RETURNED FOR LANDING. REMOVED AND REPLACED THE LT MLG RETRACT ACTUATOR IAW AMM 32-31-46-04. LEAK CHECK AND OPS CHECKED GOOD WITH NO DISCREPANCIES NOTED.