What was found
NR 1 ENG FIRE ON GROUND-LOUD BANG, FOLLOWED BY SMOKE, FOLLOWED BY NR 1 ENGINE FIRE WARNING ENGINE FIRE AND SEVERE QRH COMPLIED WITH AS WELL AS ALL APPLICABLE CHECKLISTS. NR 1 FIRE BOTTLE FIRED, NR 1 PACK ON-TEMP 38C GOOD FIRE TEST. REMOVED AND REPLACED NR 1 ENG PER MX WORKCARD 71T0701-1 RAN ENG PER JRH, OPS CHECKS AND LEAK CHECKS NORMAL.