What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO CUN DUE TO THE FLIGHT CREW REPORTING THAT ON INITIAL CLIMB ENGINE 1 NACELLE TEMP RAPIDLY CLIMBED TO 330C. TEMPERATURE DECREASED WITH POWER REDUCTION. THE FLIGHT CREW ADVANCED THE ENGINE POWER BACK TO CLIMB POWER AND ENGINE 1 NACELLE TEMP AGAIN RAPIDLY INCREASED TO 350C. TEMPERATURE WOULD CONSISTENTLY INCREASE WITH THRUST INCREASE. THE AIRCRAFT LANDED SAFLEY AT CUN AND TAXIED TO THE GATE UNDER ITS OWN POWER. MAINTENANCE REPLACED THE NACELLE TEMPERATURE HEAT DETECTOR FOR #1 ENGINE AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK PER AMM 75-41-15.