What was found
AFTER DEPARTURE, APPROXIMATELY 1,000 FEET MSL, AVIONICS SMOKE OVERHEAD ALERT, MASTER WARNING BELL AND ECAM ALERT. COMPLIED WITH ECAM AND QRH. EMERGENCY DECLARED. NO REFERENCE REQUIRED PER CREW INPUT NO SMOKE WAS NOTICED IN THE COCKPIT, ONLY THE INDICATION OF AVIONICS SMOKE ALONG WITH WARNING BELLS AND ECAM ALERT. R/I PREMATURE REMOVAL/INSTALLATION AMM: 26-15-12-04 AMM: 26-15-00-05 TESTED SNIFFER FAN. OPS OK & NO SMOKE ODOR. RAN BOTH PACKS. NO OIL/HYD ODOR OR SMOKE. FOUND COCKPIT DUCT DETECTOR FAILED. R & R COCKPIT DUCT SMOKE DETECTOR (13WA). OPS CK OK.