As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ABRUPT PITCH DOWN 80 FEET BELOW CRZ. AP 1+2 COMPENSATED WITH SEMI ABRUPT PITCH UP. WENT 60 FEET ABOVE CRZ THEN DAMPENED OUT. DID TRBS IN AP 1+2 AND WITHOUT AP. ACFT PORPOISED AFTER THE REPLACEMENT OF RT YELLOW SYS ELEV SERVO VALVE 34CE2 PCN 644-9014. RT YELLOW SYS ELEV SERVO VLV 34CE2 NEEDS TO BE REPLACED REF LM1348. REMOVED RT INBD ELEVATOR SERVO CONTROL. NEW ONE IN POSITION. NEEDS INSTALLATION PER MM. INSTALLED SERVO VALVE 34CE 2 PER AMM.