As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR RETURN DUE TO NR 1 GEN LOW OIL PRESSURE LIGHT ILLUMINATED DURING TAKEOFF. DISCONNECTED NR 1 CSD. APU FIRE DETECTION SYSTEM INOP. AIRCRAFT MADE AN UNEVENTFUL LANDING. REMOVED AND REPLACED NR 1 CSD ASSYS PER BOEING MM. RAN ENGINE OPS CK'D OK AND CHANGE IN LINE FILTER LEAK CK'D OK.