As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT A/C LOST PRESSURIZATION, ALT ON PRESS GAUGE WENT FROM 0 TO CURRENT ALTITUDE. RATE WENT FROM -500FT (NORMAL) TO THE RATE AT WHICH DESCENDING. DIFF WENT TO 0. HUMMING NOISE HEARD FROM BEHIND COCKPIT. NO ALERT OR CAUTION INDICATING A PROBLEM. REMOVED AND REPLACED PNEUMATIC OUTFLOW VALVE IAW JIC NR 21-31-22. REMOVED AND REPLACED MANUAL PRESS CONTROLLER IAW JIC NR 21-32-82. PERFORMED FUT CK ON GND IAW JIC NR 21-31-00. OP CK OK.