What was found
20 MILES, PLANE IN CLEAN CONFIG, GOT SERIOUS VIBRATION. CHECKED ENG INSTRUMENTS & SAW NR 2 ENG WAS 15% LESS ON N2 COMPARED TO OTHER ENGS. EGT STARTED TO CLIMB, SAW 690 DEG BEFORE WE SHUT DOWN ENG. DID FULL QRH PROCEDURE FOR ENG FIRE SEVERE DAMAGE. PULLED FIRE HANDLES & DISCHARGED AGENT. R & R PT2 TT2 SNS IAW MM 73-21-06-4-2. NEED OPERATIONS TEST, PERFORMED HIGH POWER ENG RUN WITH JRH. RAN NR 2 ENG TWO TIMES & PARAMETER WERE COMPARED WITH NR 3 ENG. ALL PARAMETER IS NORMAL WITH NO VIBRATION FELT.