As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT STARTED AN UNCOMMANDED CLIMB. CAPTAIN MANUALLY DISCONNECTED THE AUTOPILOT. CAPTAIN INSTRUMENTS SHOWED CWS-P, A CLIMBING ALTIMETER, AND A VSI SHOWING A DECENT. FIRST OFFICER INSTRUMENTS NORMAL. THEN IRS, L-DRIFT MESSAGE FOLLOWED BY COMPART IRS 1-2 THEN IRS FAULT. REMOVED AND REPLACED L ADIRU IAW AMM 34-21-01, OPS CHECKED GOOD. ACCOMPLISHED HUD OPS TEST 34-36-00-501.