As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ACARS "NO COMM" WHEN HF NR 2 SELECTED TO DATA. ATTEMPTED SEVERAL TIMES AT ONE HOUR INTERVALS TO RE-ESTABLISH COMM. HF VOICE WORKED NORMAL. NR 1 HF DATA WORKED NORMAL. UNABLE TO VERIFY DISCREPANCY. ACFT ACARS USES HF DATA WHEN OUT OF VHF DATA RANGE. REPLACED NR 2 TRANSCEIVER PRECAUTIONARY.