As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT 3399, YELLOW HEADING ON EHSI COMING ON INTERMITTENTLY DURING FLIGHT. ATTEMPTED TO SAVE SEVERAL TIMES DURING STRAIGHT AND LEVEL, NO CORRECTIONS NOTICED. MAINTENANCE REINITIALIZED BOTH AHRS SYSTEMS. ALL CHECKS GOOD IAW SF-340 MM CHAP 34.