As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LANDING GEAR WOULD NOT EXTEND WHEN HANDLE WAS PLACED DOWN. PERFORMED "GRAVITY EXTENSION" IAW QRH. EMERGENCY DECLARED AND ACFT WAS STOPPED ON THE RUNWAY BECAUSE OF NWS. LOOKED AT BOTH SYS 1 & 2 BEFORE EXTENDING GEAR MANUALLY. R & R LANDING GEAR SELECTOR VALVE IAW AMM 32-31-12-04, ALL TESTS AND LEAK CHECK GOOD. ACFT OK FOR SERVICE.