As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PACK 2 CHRONIC TRIP. DUE TO CONTINUED REPORTS OF PACK 2 TRIP AND SUBSEQUENT RESET PLEASE ACCOMPLISH A CHECK OF THE PRIMARY HEAT EXCHANGER WITH REFERENCE TO MM FOR ANY OBSTRUCTIONS OR ISSUES THAT MAY RESTRICT AIRFLOW THROUGH THE ECHANGER. REPLACED LOW LIMIT VALVE. CHECKS OK REF AMM 21-52-03. FIM TASK 21-51-81 8, PAGE 256 PARA 6. [BUTTERFLY SHEARED ON SHAFT OF OLD VALVE.