What was found
(CAN) ON CLIMBOUT, THE LT ENGINE FWD UPPER COWLING, AFT RT SIDE COWL LATCH, FAILED OPEN IN FLIGHT IN THE LOCKED POSITION. ACFT RETURNED TO AIRPORT WITHOUT FURTHER PROBLEMS. MAINTENANCE REMOVED COWLING, INSPECTED, LUBRICATED LATCH, REINSTALLED COWLING AND RETURNED ACFT TO SERVICE. MAINTENANCE DID NOT REPORT ANY PROBLEM WITH LATCH OR CAUSE FOR LATCH OPENING.