As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STBY GYRO DISPLAYED "EXT MANUV" ANNUNCIATOR AND SHOWED A 10 DEGREE RT BANK AND HEADING PRECESS OF MORE THAN 180 DEGREES. HEADING PRECESS ABOUT 10 DEGREES EVERY 2 MINUTES. REPLACED STANDBY GYRO (SECONDARY FLIGHT DISPLAY) WITH REPAIRED UNIT, OPS CHECKED NORMAL. WORK PERFORMED IAW THE MM 34-21-17.