What was found
WHILE ON CLIMBOUT, A PASSENGER ALERTED THE FLIGHT ATTENDANT THAT THE RIGHT HAND INBOARD FORWARD COWLING DOOR WAS OPEN. THE FLIGHT ATTENDANT NOTIFIED THE PILOT WHO CONTACTED THE TOWER THAT FLIGHT 4090 WAS RETURNING AND REQUESTED A HOLD TO BURN OFF EXCESSIVE FUEL. FLIGHT 4090 LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE INSPECTED AND FOUND THE LATCHES WERE LATCHED BUT THE COWLING WAS OPEN. THERE WAS NO DAMAGE NOTED. MAINTENANCE RELATCHED THE LATCHES AND THE AIRCRAFT WAS RELEASED FOR SERVICE. FLIGHT 4090 DEPARTED WITHOUT FURTHER INCIDENT.