As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE FLIGHT, CARGO SMOKE WARNING LIGHT ILLUMINATED IN THE COCKPIT. THE CREW DECLARED AN EMERGENCY AND RETURNED TO FIELD. MX CREW INSPECTED CARGO BAY AND FOUND NO EVIDENCE OF SMOKE. THEY TESTED THE SYS AND NO FAULTS WERE FOUND. THE ACFT WAS FERRIED BACK TO DEPARTURE WHERE THEY STARTED TESTING IT FURTHER. AT THAT TIME MX WAS GETTING A FAILURE INDICATION ON THE NR 2 SMOKE DETECTOR. THE NR 2 SMOKE DETECTOR WAS CHANGED AND AN OPS TEST WAS PERFORMED WITH SATISFACTORY RESULTS.