As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING RUNUP, IT WAS NOTICED THAT HYDRAULIC PRESSURE WARNING FAILED TO EXTINGUISH UNTIL AIRCRAFT WAS RUN-UP ABOVE IDLE TO FLIGHT IDLE SPEED. SUBSEQUENT INVESTIGATION REVEALED NO FLUID RETURN TO THIS PUMPS RESERVOIR. REPLACEMENT OF THE PUMP CORRECTED THE PROBLEM. EXTERNALLY THE REMOVED PUMP APPEARED NORMAL. PUMP RETURNED TO MFG FOR INSPECTION. THIS IS A 2-PUMP HYDRAULIC SYSTEM. (K)