What was found
DURING PREFLIGHT CHECKS, THE TEST FEATURE OF THE LIQUID LEVEL SENSOR WAS ACTIVATED & TESTED IAW THE BEFORE START CHECKLIST RESULTING IN A GOOD ACTIVATION TEST WITH A CAS MESSAGE ON THE MFD REPORTING HYD LOW LEVEL AS IT SHOULD. THE TEST FUNCTION WAS DEACTIVATED WHICH SHOULD HAVE REMOVED THE HYD LOW LEVEL CASS MESSAGE BUT IT REMAINED ILLUMINATED. A VISUAL OF HYD FLUID LEVEL REVEALED THE HYD FLUID LEVEL WAS SET TO THE CORRECT LEVEL. TROUBLESHOOTING REVEALED THE LIQUID LEVEL SENSOR WAS INDICATING INCORRECTLY. TIME TO CHANGE PART WAS 2.5 MAN HOURS. TOTAL TIME ON PART AT FAILURE 225 FLIGHT HOURS. DURING PREFLIGHT IT WAS NOTED ON INITIAL POWERUP, THE HYD LOW LEVEL CASS MESSAGE ILLUMINATED. A VISUAL OF THE HYD FLUID LEVEL REVEALED THE HYD FLUID LEVEL WAS SET TO THE CORRECT LEVEL. TROUBLESHOOTING REVEALED THE LIQUID LEVEL SENSOR WAS INDICATING INCORRECTLY. IT WAS BROUGHT TO NOAA’S ATTENTION THAT ENGINEERING STANDARDS FOR THIS PART HAD RECENTLY CHANGED & THERE WAS A RASH OF THESE BEING CHANGED & THE REDUCED STANDARDS WERE STILL THE CURRENT PRODUCTION STANDARDS. NOAA REPORTED THEY WILL MDR EACH FAILURE. TIME TO CHANGE PART WAS 2.5 MAN HOURS. TOTAL TIME ON PART AT FAILURE 60.9 FLIGHT HOURS.FM109'S HYD LOW SENSOR HAS NOW FAILED 3 TIMES SINCE WE ACCEPTED THE AIRPLANE.