As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING SCHEDULED 12-MONTH TESTING OF CABIN ALTITUDE WARNING SYS NOTED ANNUNCIATOR INDICATION COMING ON AT 9,940 FT ALTITUDE; BELOW 10,000 FT MINIMUM SERVICE LIMIT ALTITUDE. REPLACED PN 101-384028-33 BAROMETRIC SWITCH WITH IMPROVED PN 101-384028-47 SWITCH ASSY. HAVE NOTED SAME OLDER PN SWITCH TO FAIL OUT-OF-TOLERANCE IN OTHER SERIES ACFT. RECOMMEND MFR ISSUE A RECOMMENDED TYPE SB TO REPLACE OLDER STYLE BAROMETRIC SWITCHES WITH IMPROVED PN SWITCH.