As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE AIRCRAFT FACTORY INSTALLED ACU BEGAN FAILING AT 200 HOURS (INTERMITTENT ALTERNATOR DROPPING (OFF LINE) FOR A FEW SECONDS) (ON ONE OCCASION, THE FIELD CB DISENGAGED) A NEW ACU WAS INSTALLED AT 215.9. AT 246.1 THE SAME PROBLEM SURFACED, AND THE THIRD ACU WAS INSTALLED. THE SERVICE CENTER HAS HAD THE SAME PROBLEM WITH OTHER AC. (K)