As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LOST PRESSURIZATION AT FL 290. PRESSURE CONTROLLER WOULD NOT LOCK. DESCENDED TO 2000, GAINED MANUAL CONTROL. DECLARED AN EMERGENCY. TROUBLESHOOTING DISCOVERED R2-55 RELAY TO BE BAD, REPLACED RELAY. ALSO REPLACED R20227. REPLACED LEFT GROUND SHIFT RELAY R2-4. PERFORMED ADJUST/TEST OF CABIN PRESSURE CONTROL IAW DC-9 AMM 21-32-00, PAGE A & B THROUGH COMPLETION. ALL OPS CHECKED GOOD. SEE WORK PACK 2005990 FOR WORK ACCOMPLISHED.