As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA FLIGHT NR 2433: IN AUTO MODE, PRESSURE WOULD VARY 1 FULL SCALE IN RATE. RAN PRESSURE FAIL CHECK LIST. MANUAL PRESSURE DIDN'T WORK CORRECTLY. IN AUTO WITH BLEEDS SELECTED IN MAX, PRESSURE WAS MORE STABLE. MAINTENANCE REPLACED FWD SAFETY VALVE IAW Q400 MM TASK 21-31-00-000-801 AND 21-31-00-400-801. CHECKS GOOD. AIRCRAFT RETURNED TO SERVICE.