As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RUDDER AND AILERON TRIM FROZE IN FLIGHT AT FL310, TEMP -32*C. TRIM WORKED NORMAL DURING DESCENT TO LOWER ALTITUDE FL250, TEMP -12*C. MAINTENANCE PERFORMED THE REQUIREMENTS FOR THE RUDDER AND AILERON LUBE. A SUCCESSFUL OPERATIONAL CHECK FLIGHT WAS PERFORMED. AIRCRAFT WAS RETURNED TO SERVICE.