What was found
PASSENGER REPORTED FLAMES COMING FROM NUMBER #1 ENGINE JUST BEFORE TAKEOFF. WE CLEARED THE RUNWAY AND CALLED FOR CFR. CFR REPORTED NO DAMAGE FROM THE SHUT (#1) DOWN ENGINE. NO ABNORMAL ENGINE INDICATIONS. CFR REPORTED NO DAMAGE FROM THE SHUT DOWN ENGINE. TAXIED BACK TO GATE SINGLE ENGINE. NO ABNORMAL ENGINE INDICATIONS. PERFORMED FIM 71-05 TASK811, PARAGRAPH C1 AND D1 THRU 4. PERFORMED ENG VENT AND DRAIN INSPECTION IAW AMM 71-71-00 PARAGRAPH 2G8. DUE TO HISTORY OF OIL PUDDLING IN TAIL PIPE, PP ENGINEERING WILL SCHEDULE AFT SUMP REPACK AND CENTER VENT TUBE CLEANING.