As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMF - CREW COMPLIED WITH ABNORMAL CHECKLIST AND ALTERNATE GEAR EXTENSION WHEN AFTER GEAR WAS SELECTED DOWN, THE GEAR DID NOT EXTEND. GEAR LOWERED NORMALLY WITH THE ALTERNATE EXTENSION AND THE LANDING WAS UNEVENTFUL. MAINTENANCE INSPECTED THE AIRCRAFT AND REPLACED THE MAIN LANDING GEAR SELECTOR VALVE. LEAK CHECKS, OPERATIONAL CHECKS INCLUDING EXTENSION AND RETRACTION CHECKS WERE GOOD. AIRCRAFT RETURNED TO SERVICE.