As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED. AT FL340 OBSERVED SPURIOUS NR 2 ENGINE EICAS FIRE WARNING FOR APPROXIMATELY 3 SECONDS. ALL ENGINE INDICATIONS NORMAL. REMOVED AND REPLACED 5LP INTERFACE BOARD PER AMM 33-14-33. OPERATIONAL TEST GOOD. ACCOMPLISHED BITE CHECK IAW AMM 26-12-00 THRU FDIU WITH NO FAULTS FOUND.