As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IN FLIGHT, THE INSTRUMENT VACUUM SYSTEM WOULD NOT PUT OUT PROPER SUCTION AND CAUSED THE ATTITUDE INDICATOR TO TUMBLE. THE AC RETURNED TO MAINTENANCE AND AN INSPECTION OF THE SYSTEM FOUND THAT THE PUMP WAS WEAK. PUMP WAS REMOVED AND A NEW PUMP INSTALLED. OPERATIONAL CHECK OF THE SYSTEM CHECKED NORMAL. (K)