As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AFTER A NORMAL ENGINE START AND WHILE SITTING AT IDLE RAMP PERSONNEL AND AIRCRAFT BEHIND US REPORTED MULTIPLE FLAMES SHOOTING OUT OF TAIL PIPE. NO UNUSUAL INDICATIONS IN COCKPIT. CHECKED NR 1 ENGINE IAW FIM 71-05-00-810-811-F00 AND AMM 71-00-00-800-803-F00 AND MCM CARD 4917 ENGINE SCREENS AND MAGNETIC SCIP DETECTOR. NO DEFECTS FOUND OK FOR SERVICE.