As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FOUND THE APOLLO ALT ENCODER PLUS 700 FEET ON INITIAL EVALUATION. ADJUSTED AND RAN IT UP TO 20,000 FEET AND ERRORS WERE WITHIN ACCEPTABLE TOLERANCE. REPAIRED A STATIC LEAK (OPEN) AT THE PITOT STATIC MAST ASSY AND CHECKED STATIC AND TRANSPONDER GOOD. COULD NOT ISOLATE CAUSE OF 'INVALID' TO SPECIFIC COMPONENT.