As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) EXCESSIVE GREASE WAS APPLIED TO THE REAR ROTOR BEARING DURING OVERHAUL. SOME OF IT ESCAPED AND WAS FLUNG ONTO THE BRUSHES AND SLIP RINGS, FOULING THEM AND CAUSING A BUILDUP OF GREASE AND CARBON ON THE SLIP RINGS AND BRUSH FACES. THE ELECTRICAL RESISTANCE INCREASED AND THE FIELD CURRENT WAS REDUCED TO THE POINT THAT THE ALTERNATOR WAS UNABLE TO KEEP UP WITH THE AIRCRAFT`S REQUIREMENTS. (TC NR 20070913002)