What was found
CREW REPORTED DURING POSTFLIGHT INSPECTION, A LONG THICK STREAK OF BLACK SOOT COMING FROM OTBD GENERATOR VENT ON NR 2 ENGINE ACCOMPANIED WITH SCHRAPNEL AND DEBRIS HANGING OUT OF VENT. MX INSPECTED AND FOUND THE NR 4 ENGINE GENERATOR TO HAVE COME APART DURING OPERATION DUE TO SUSPECTED BEARING FAILURE. MX R & R NR 4 GENERATOR, CARBON SEAL, WIRE HARNESS, HYD LINE, WITH OPS CHECKS SUCCESSFUL. ACFT WAS APPROVED FOR RETURN TO SERVICE.