As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT AT 2500 FT. ONE SET OF BRUSHES IN THE STARTER GENERATOR FAILED. THE GENERATOR WAS STILL PUTTING OUT 28 VDC THROUGH THE REMAINING BRUSHES SO THE GENERATOR WARNING LIGHT DID NOT ILLUMINATE. THE GENERATOR WAS NOT PUTTING OUT ENOUGH CURRENT IN ITS DAMAGED STATE TO KEEP THE AIRCRAFT BATTERY CHARGED. THE AIRCRAFT BATTERY SLOWLY LOST VOLTAGE TILL ALL AIRCRAFT ELECTRICAL POWER FAILED WITHOUT WARNING.