As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING GROUND FUNTIONAL TEST OF THE INITIAL INSTALLATION OF AIR DATA COMPUTER (ADC) INSTALLED AS PART OF THE CHELTON FLIGHT SYSTEMS EFIS-SV SYSTEM UNDER STC SA02203AK, ENCOUNTERED 100FT ALTITUDE DRIFT WITHIN 5 MINUTES AFTER BAROMETRIC PRESSURE HAD BEEN SET.