As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT MADE A RAPID DESCENT FROM FL240 TO 10000 FEET DUE TO A PRESSURIZATION PROBLEM. TWO DRAIN VALVES WERE FOUND FAILED OPEN. THE FAILED DRAIN VALVES WERE REPLACED, THEN ADJUSTMENT/TEST PROCEDURE WERE ACCOMPLISHED ON THE PRESSURIZATION SYSTEM. A TEST FLIGHT WAS ACCOMPLISHED FOR SYSTEM INTEGRITY.