As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WITH A/P ENGAGED AND SPEED BRAKE EXTENDED TO FULL UP POS. ON DESCENT PLANE TRIED TO NOSE DIVE UP TO 10 DEG NOSE DOWN. DESCENT RATE WENT TO 5880 FPM. DISENGAGED A/P WORKED FINE. TRIED A 2ND TIME WITH A/P ENGAGED SAME PROBLEM. WITH A/P DISENGAGED USED SPEED BRAKE TWICE WITH NO NOSE DOWN EXCESS.