What was found
AFTER DEPARTURE FROM MQT INTO IMC, THE EADI'S BEGAN TO DRIFT TO THE LEFT TO APPROX 20 DEGREES OFF RUNWAY HEADING. DURING TURNOUT THE HDG FLAGGED ON BOTH EADI'S. AFTER LEVELING OFF CONFIRMED THE EADI'S WERE OFF COMPASS HEADING BY 50 DEGREES. RECEIVED RMI FLAGS ON BOTH RMI'S. TRIED THE NR 1 INVERTER, NO CHANGE. A/C DIVERTED TO ESC. MAINTENANCE REPLACED NR 1 INVERTER P/N PC251-123C, S/N OFF 9123, S/N ON 8198. NR 1 INVERTER CHECKS GOOD IAW SF340 MM CH 24. RESET NR 1 AND NR 2 AHRS COMPUTERS. NR 1 AND NR 2 AHRS CHECK GOOD IAW SF340 MM CH 34.