As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FL390 AP/FAIL, ATT FAIL, HDG FAIL COPILOTS SIDE STBY HSI FAIL. YAW DAMP WOULD NOT RE-ENGAGE. WHEN PUSHING TCS BUTTON FOR FLIGHT DIRECTOR AP FAIL LIGHT WOULD ILLUMINATE AND COULD BE EXTINGUISHED BY PRESSING AP DISCONNECT BUTTON. REMOVED AND REPLACED NR 2 AHRS UNIT. OP CHECK GOOD. IAW MM 34-21-01.