What was found
LGA - DURING TAXI BACK TO GATE AFTER LANDING. PILOT WAS NOTIFIED VIA RAMP CONTROL THAT ANOTHER AIRCRAFT APPARENTLY SAW SPARKS AND FLAMES COMING FROM THE NR 2 ENGINE EXHAUST. THE CREW DID NOT HAVE ANY INDICATION OF FIRE FROM MASTER CAUTION PANEL. MAINTENANCE CONDUCTED A FULL INSPECTION OF THE ENGINE AND FOUND NO ABNORMALITIES, AND NO EVIDENCE OF FIRE RAN ENGINES AT LOW POWER. COULD NOT DUPLICATE. AIRCRAFT WAS RELEASED FOR FLIGHT. (M)