As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(5APR) PILOT REPORTS: INTERMITTENT PROPELLER TONE CHANGE IN CRUISE, NP INDICATION DROP INTO THE 700'S (RPM'S) ALL OTHER INDICATIONS NORMAL. VISUALLY INSPECTED THE BETA RING AND CABLE. CLEANED AND DRIED ELECTRICAL CONNECTION AT THE CSU (PROPELLER GOVERNOR)FOR THE PROPELLER SPEED INDICATION. NO DEFECTS NOTED. ENGINE RAN BY THE CREW WITH NO DEFECTS NOTED. THE PN FOR THE PROPELLER GOVERNOR IS 968.20.13.160 AND THE OTHER GOVERNOR COMPANY PN IS 8217-137.