What was found
RIC - ON CLIMB-OUT, THE LEFT ENGINE INDICATED A POWER LOSS (RPM DROPPED TO 13,800 AT MAX). THE CREW DECLARED AN EMERGENCY AND RETURNED TO RIC. DURING DESCENT, LEFT GENERATOR LIGHT, LEFT ALTERNATOR LIGHT, AND LEFT GEARBOX OIL PRESSURE LIGHT CAME ON. ALL TEMPERATURES WERE NORMAL. THE AIRCRAFT LANDED WITHOUT ANY OTHER PROBLEMS. AFTER TROUBLESHOOTING, MECHANIC FOUND INTERNAL FAILURE IN THE LEFT GEARBOX.