What was found
(CAN) ON MAR 18, 2002, CREW EXPERIENCED FLUCTUATING NP&TQ, POWERPLANT MESSAGE & PEC NR 1 CAUTION LIGHT WERE PRESENTED. WHEN POWER REDUCED, FOR DESCENT, NR 1 NP OVERSPEED. ENGINE SHUTDOWN. UNEVENTFUL LDG ACCOMPLISHED. FAULT CODES 719,939,998,718,161&999 REPORTED. PCU & PEC WERE REPLACED. FAULT CODES REMAINED. MPU PROBE REPLACED & ENGINE BEING GROUND RUN TO COMPLY WITH PROCS REQD FOLLOWING PEC & PCU REPLACED. MAINT RAN ENGINE & ABOUT 2 MINS INTO RUN ANOTHER INCIDENT OCCURRED. ENGINE AT DETENT POWER, WHEN LARGE BANG HEARD, FOLLOWED BY FIRE WARNING. ENGINE SHUTDOWN, & 1ST FIRE BOTTLE DISCHARGED. SOME TIME LATER ESTIMATED TO BE 30 SECONDS, FIRE WARNING STILL APPARENT.