As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FIRE WARNING BELL, WITH NO WARNING LIGHT DURING FLIGHT. THE FIRE WARNING BELL SOUNDED MULTIPLE TIMES AT SEEMINGLY RANDOM INTERVALS AND DURATIONS THE BELL WAS NOT ASSOCIATED WITH A FIRE WARNING LIGHT, SO THE FLIGHT WAS ABORTED AND THE AIRCRAFT RETURNED TO BASE WITH NO FURTHER INCIDENT.