What was found
(CAN) DURING CRUISE AT FL390, THE LT ENGINE ROLLED BACK AND SHUTDOWN. AN EMERGENCY WAS DECLARED. AT 10,000 FT. AN IN-FLIGHT WINDMILL START WAS SUCCESSFULLY ACCOMPLISHED. ALL ENGINE PARAMETERS WERE NORMAL PRIOR TO THE EVENT, AND ALSO FOR THE REMAINDER OF THE FLIGHT AFTER IT WAS RESTARTED. SUBSEQUENT MAINTENANCE PERFORMED AFTER LANDING REVEALED NO ANOMOLIES. ALL FILTERS, SUMPS, AND CHIP DETECTORS WERE INSPECTED AND WERE ALL FOUND TO BE NORMAL. THE FCU WAS REPLACED AS A PRECAUTION.