As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMB-OUT HEARD A LOUD WHINNING NOISE, HYDRAULIC CAUTION LIGHT CAME ON AND NR 1 HYDRAULIC PRESSURE WENT TO ZERO. STARTED EMERGENCY CHECK LIST AND NOISE STOPPED AND PRESSURE CAME BACK UP. MOMENTS LATER NOISE RETURNED AND PRESSURE DROPPED TO ZERO. MAINTENANCE REPLACED THE PACKING AND RETAINER MS28773-06 ON THE HYDRAULIC PUMP DISCHARGE FITTING.