As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED THAT THE AFT TRIM AIR VALVE FAILED. THE MAINTENANCE VENDOR VERIFIED THE DISCREPANCY ACCESSED THE DEFECTIVE AIR VALVE AND REPLACED WITH A MODIFIED UNIT. OPS AND LEAK CHECKS WERE SATISFACTORY. THE AIRCRAFT WAS THEN RETURNED TO SERVICE