As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING C CHECK AND FUNCTIONAL TEST, THE ALTITUDE PRESSURE SWITCH FAILED ITS FUNCTIONAL TEST. MAINTENANCE REMOVED AND REPLACED THE ALTITUDE PRESSURE SWITCH IN ACCORDANCE WITH THE REQUIREMENTS OF AMM 35-23-15 PB 401. FOLLOWING ITS INSTALLATION AND INSPECTION, IT OPERATIONALLY CHECKED GOOD.