As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ACARS "NO COMM" FOR 3 PLUS HOURS. APPEARS THAT HF PORTION IS INOPERATIVE. PERFORMED HF LINK TEST IAW MM 23 27 00 730 803 004 PARAGRAPH D.8. CONFIRMED FAILURE OF HF2 DATA PORTION OF SYSTEM (HF1 WORKS IAW AMM PROCEDURE). REMOVED AND REPLACED HF2 TRANSCEIVER IAW MM 23 11 21 HF2 LINK TEST PASSES IAW MM 23 27 00 730 803 044 SYSTEM TEST GOOD IAW MM 23 11 00 730 801.