As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PRESSURE LINE FROM NR 1 ENGINE DRIVEN PUMP CHAFED AT AFTMOST CLAMP LOCATION (NEAR NR 1 SYSTEM RESERVOIR) UNTIL THE LINE FAILED UNDER PRESSURE CAUSING A COMPLETE LOSS OF NR 1 HYDRAULIC SYSTEM IN FLIGHT. CLAMP CUSHION FAILED CAUSING METAL TO METAL CONTACT. SUSPECT THAT DEFECT WAS NOT READILY VISIBLE BEFORE FAILURE. (K)