What was found
(CAN) THE AIRCRAFT ORIGINALLY EXPERIENCED A GEAR WARNING SYSTEM FAILURE ON APPROACH. SUBSEQUENTLY, THE DOWNLOCK SWITCHES WERE CLEANED AND LUBRICATED AND THE SYSTEM TESTED SERVICEABLE. THE NEXT FLIGHT HAD A LT MAIN GEAR INDICATION FAILURE, EMERGENCY PROCEDURES WERE FOLLOWED AND THE LT GEAR INDICATION WORKED PRIOR TO TOUCH DOWN. THE AIRCRAFT WAS RETURNED TO MAINTENANCE AND THE LANDING GEAR SYSTEM WAS TROUBLESHOT EXTENSIVELY AND TEST FLOWN EACH TIME WORK WAS CARRIED OUT UNSUCCESSFULLY. THE SNAG ONLY OCCURRED AT HIGHER ALTITUDES OR COLDER TEMPERATURES. THE LT MAIN GEAR SWITCH WAS REPLACED DUE TO SUSPECT WATER PROPAGATION AND FREEZING. THE AIRCRAFT WAS TEST FLOWN AT THE SAME ALTITUDES AND WAS SUCCESSFUL. THE AIRC