As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE COOLING FAN IN THE STARTER GEN DEVELOPED A CRACK IN THE FAN BLADE PART (4 BLADES ARE STAMPED FROM ONE ALUMINUM PIECE, AND SWAGED ON A STEEL HUB) AT THE NOTCH BETWEEN TWO BLADES. UNDER CENTRIFUGAL FORCE AT 12,000 RPM, THE BLADES SPLIT IN TWO AND CAME OFF THE HUB. NO FOD RESULTED. VISUAL PREFLIGHT INSPECTION FOUND THE DEFECT. THIS FAN IS AN OLD DESIGN, AND HAS NOW BEEN REPLACED BY A SUPERSEDING PART THAT IS A ONE-PIECE CAST ALUMINUM FAN.