As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT SUCTION PRESSURE READING DROPPED TO ZERO, DURING FURTHER TROUBLESHOOTING, TECH FOUND THE ENGINE DRIVEN AIR PUMP WAS NOT PRODUCTING ENOUGH SUCTION. PROBABLE CAUSE COULD BE FROM PISTION WEARING INSIDE OF PUMP. RECOMMENDATION AT THIS TIME IS FOR THE MFG TO INVESTIGATE WHY PUMP PISTON IS FAILING. (K)