As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE LT ENGINE N1 TACHOMETER GENERATOR DID NOT RESEMBLE THE OTHER TACHOMETER GENERATORS. INVESTIGATION FOUND VENDOR-ADVANCE POWER, INC., IS NOT AN APPROVED CESSNA/CITATION VENDOR FOR THIS PART. ENGINE LOG BOOK SHOWS A CITATION PART NUMBER WHEN THIS UNIT WAS INSTALLED. THIS UNIT WAS BLACK IN COLOR AND SMALLER IN DIAMETER THAN THE APPROVED UNITS.