What was found
OXY LO PRES YELLOW CAS - UNABLE TO COMPLETE PRE-FLIGHT OF OXYGEN MASK/SYSTEM. OXYGEN PRESS ON MFD SHOWS 1900 PSI / FULL. AMBER CAS MSG APPEARS DURING TEST AND SYSTEM WILL NOT TEST BUT ONCE. TRIED TO RESET CUT OUT SEVERAL TIMES BUT MSG REMAINS ILLUMINATED FOR AWHILE THEN GOES OUT BUT REAPPEARS WHEN STARTING TO TEST SYSTEM. TROUBLE SHOT OXYGEN SHUT OFF AND FOUND ACTUATOR CABLE TO SHORT TO RIG CORRECTLY. INSTALLED REPLACEMENT CABLE PER PHENOM 300 MM 35-01-04 AND FOUND THAT CABLE DID NOT EXTEND THROUGH THE OXYGEN BOTTLE ON/OFF LEVER NUT 1 MM AS PER MM INSTRUCTIONS. ADJUSTING CABLE TO ACHIEVE 1 MM OF FEED THROUGH CAUSES CABLE NOT TO ACHIEVE FULLY "ON" DETENT OF THE OXYGEN BOTTLE. ORDERED ANOTHER CABLE. REMOVED AND REPLACED OXYGEN CONTROL CABLE IAW EMBRAER PHENOM 300 MM 35-01-04. OPS CHECK GOOD IAW PHENOM 300 MM 35-01-04. P/N OFF AND ON - 4441708-000.