What was found
(CAN) THE RT LANDING LIGHT HAS A HISTORY OF FAILING WITHIN A VERY SHORT PERIOD OF TIME FOLLOWING REPLACEMENT OF BULB. THE LASTEST INCIDENT OCCURRED WITHIN 5 HOURS OF FLYING TIME. MAINTENANCE FOUND THAT THE SEALED LAMP WAS CRACKING AT THE TOP OF THE LENSE ON A CONSISTANT BASIS. LOCATATE AT THE TOP OF THE LIGHT ASSEMBLY A RE (3) RIVETS, WHICH WERE COMING IN CONTACT WITH THE BACK OF THE SEALED LAMP. ANTI-CHAFE TAPE WAS ADDED TO THE INSIDE DIAMETER OF THE LIGHT HOUSING, EFFECTIVELY ADDING A SHIM. THIS HAS PROVIDED ENOUGH CLEARANCE BETWEEN THE HOUSING AND LIGHT TO CORRECT THE PROBLEM. THE AIRCRAFT HAS NOT EXPERIENCED ANOTHER LIGHT FAILURE SINCE THE MAINTENANCE ACTION WAS ACCOMPLISHED.