What was found
PASSENGERS SAW AND HEARD FLAMES AND BANGS COMING OUT OF THE NR 1 ENGINE. RETUNED TO THE GATE. DURING FLAMES AND BANGS, NO INDICATION IN THE FLIGHT DECK AND DID NOT HEAR BANGS. TAXIED ACFT & PERFORMED HIGH POWER RUN WITH OBSERVER, NO FAULTS, FLAMES OR BANGS IAW AMM 71-00-00. ALL INDICATIONS NORMAL. PPE AGREES WITH RESOLUTION. OK FOR SVC. INSPECTED NR 1 ENG EXHAUST, NO DEFECTS IAW FIM 71-05 TASK 811.