As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BOTH HF RADIOS WOULD TUNE BUT TRANSMISSION AND RECEPTION GARBLED AND UNREADABLE. ACFT GROUNDED. VERIFIED REU AUDIO PATH USING SATCOM IAW AMM 23-15-00-730-801, NO DEFECTS NOTED. REMOVED AND REPLACED THE NR 1 AND 2 HF TRANSCEIVERS IAW AMM 23-11-21/401. TRANSMITION AND RECEPTION AUDIO CHECKED SATISFACTORY AT TRANSCEIVER AND CAPTAINS AUDIO PANEL.