What was found
CLT FLT 1408 EN-ROUTE SFO - CLT. DURING DESCENT, AT APPROXIMATELY FL 290, A RUMBLING SOUND DEVELOPED WITH A COINCIDING RISE IN EGT TO THE REDLINE LIMIT OF THE NUMBER 1 ENGINE. PASSENGERS REPORTED SEEING FLAMES COMING OUT OF THE NUMBER ONE ENGINE TO THE CABIN CREW. THE FLIGHT CREW ELECTED TO SHUT DOWN THE NUMBER ONE ENGINE AND DECLARE AN EMERGENCY INBOUND TO CLT. FLIGHT LANDED WITHOUT FURTHER INCIDENT. TOTAL SINGLE ENGINE TIME WAS 18 MINUTES. INITIAL MAINTENANCE INSPECTION REVEALED OIL IN THE TAILPIPE. A BORESCOPE INSPECTION REVEALED NO FINDINGS CONSISTENT WITH THE ENGINE SHUTDOWN. THE OIL IN THE TAILPIPE WAS FOUND TO BE A NORMAL CONDITION FOR AN ENGINE THAT HAS BEEN WINDMILLING. MAINTENANCE TROUBLESH