As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPON FLIGHT RETURN TO DEPARTURE, THERE WAS A BEEPING IN THE HEADSET THAT SOUNDED LIKE THE FIRE WARNING GONG BUT THERE WAS NO LIGHTS OR ANY WARNINGS AND COULD CANCEL THE GONGING ONLY TO HAVE IT COME ON AGAIN AND INTERMITTENTLY. CONTINUED MONITORING ALL OTHER INSTRUMENTS AND FLEW BACK TO DEPARTURE WITH NO OTHER OCCURRENCES, REPORTED TO MX. (K)