As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) LANDING GEAR FAILED TO EXTEND WHEN SELECTED, ALTERNATE EXTENSION NORMAL. NO EMERGENCY DECLARED. MAINTENANCE FOUND THE SELECTOR VALUE UNSERVICEABLE, NEW SELECTOR VALVE IN WING ROOT P/N 57420-5 INSTALLED, FUNCTION CHECKS CARRIED OUT AND A/C RTS (SEE ALSO CASA SDR #2019611953806/611953806) (TC# 20190618009)