As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: PILOT REPORTS LANDING GEAR WARNING HORN SOUNDED FOR 20-30 SECONDS ON CLIMBOUT AT APPROX 1,000 AGL, GEAR UP, FLAPS 1 DEGREE, 2000 FPM CLIMB. MAINTENANCE REPLACED #1 AND # 2 R/A ANTENNAS IAW AMM 34-33-11. BOTH CHECK OK. ACCOMPLISHED LANDING WARNING SYSTEM TEST IAW AMM 31-51-00-730-802. SYSTEM CHECKS OK.