As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 1 HF DOES NOT TRANSMIT OR RECEIVE FROM EITHER CAPT OR FO COMM PANEL. HF 2 RECEIVES ON BOTH PANELS BUT WILL NOT TRANSMIT. THIS OCCURED 3 HOURS INTO FLIGHT. WAS WORKING FINE FOR FIRST 3 HOURS. ACFT GROUNDED. PERFORMED HF COMMUNICATION SYS TEST TASK 23-11-00-730-801. SUCCESSFUL GROUND VERIFICATION. MADE CLEAR COMMUNICATION WITH SFO RADIO. SELCAL SUCCESSUFL ALSO. NO HISTORY PAST 60 DAYS.