As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA - DURING FLIGHT, LEFT HYDRAULIC SYSTEM 'PRESS LOW' LIGHT ILLUMINATED AND PRESSURE FLUCTUATED BETWEEN 0 AND 100 PSI. LEFT SYSTEM AND THE POWER TRANSFER UNIT (PTU) WERE TURNED OFF. TIGHTENED LEAKING HYDRAULIC LINE CONNECTION TO THRUST REVERSER CONTROL VALVE, AND REPLACED PTU DAMAGED BY OPERATION WITH LOW FLUID QUANTITY. SYSTEM CHECKED OK. (M)