MECH RPT REGARDING FOLLOW-UP OF AN INFLT WRITE-UP ON AN HF XMITTER PROB. AFTER TROUBLESHOOTING THE PROB AND ACFT RELEASE; BOTH HF RADIOS FAILED INFLT.

Narrative

ON FLT FROM XXX TO ZZZ; DC-10; AN INBOUND WRITE-UP STATED THAT #1 HF WILL NOT XMIT. WHEN TUNING; TONE YYYTS 15 SECONDS. I RAN A 30 DAY HISTORY ON COMS FOR THE ACFT. NO PRIOR HISTORY NOTED. I CHKED FOR FAULTS BOTH ON THE #1 HF XMITTER AND RECEIVER; AND ON THE ANNUNCIATOR PANEL UNDER THE FE'S WORKTABLE. AGAIN NO FAULTS WERE NOTED. I THEN RE-RACKED AND CHKED FOR DAMAGED OR LOOSE CONNECTORS AND PINS. ON THE #1 HF XMITTER AND RECEIVER NO PROBS WERE FOUND. I ACCOMPLISHED A GND CHK OF THE #1 HF PER MAINT MANUAL. ALL SYS CHKED GOOD. AFTER THE FLC DID THEIR OPS CHKS; THE ACFT WAS READY TO GO. AFTER THE ACFT LEFT; I WAS TOLD THE NEXT DAY THAT ABOUT 200 MI FROM YYY TO VVV; THE ACFT HAD TO DIVERT TO ZZZ BECAUSE IT HAD LOST BOTH #1 AND #2 HF XMITTERS. THEY WERE UNABLE TO XMIT. THIS IS VERY PECULIAR TO ME HAVING LOST BOTH HF RADIOS AT THAT POINT. EVERYTHING WAS IN WORKING ORDER LEAVING LAS. THE FIX IN ZZZ WAS TO CHANGE BOTH #1 AND #2 HF XMITTERS AND COUPLERS. THE PROB WAS APPARENTLY SOLVED WITH NO REPEAT AS YET. AGAIN I STATE THAT HAVING BOTH HF RADIOS NOT TO XMIT IS VERY ODD. IN THIS SYS; THROUGH A WIRING DIAGRAM; THERE ARE 2 KEYING RELAYS AND; IF ONE WAS TO STICK THIS COULD HAVE CAUSED THE PROB. AT THE TIME I RELEASED THE ACFT; ALL SYS CHKS WERE GOOD WITH A BACKUP OPS CHK BY THE FLC. IF THIS SHOULD OCCUR AGAIN ON THIS PARTICULAR ACFT OR ANOTHER ONE; ONE SHOULD ALSO TROUBLESHOOT OR PAY CLOSE ATTN TO THE KEYING RELAYS FOR ANY FURTHER PROBS DOWN THE LINE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATES THAT HE DID TELL HIS COMPANY AND THE MAINT PEOPLE ABOUT CHKING THE 2 KEYING RELAYS FOR STICKING WHEN TROUBLESHOOTING HF RADIO PROBS. HE IS SURPRISED THAT THERE HAS BEEN NO FAA FOLLOW UP SINCE THE ACFT HAD TO DIVERT. ANALYST ALSO SPOKE WITH ACR PLTS WHO KNOW ABOUT THIS PROB. THEY ROUTINELY WILL PULL A CIRCUIT BREAKER; THEN ACTIVATE IT AGAIN WHEN SUCH A PROB OCCURS. THIS ALLOWS THE RELAY TO RELEASE AND IT WILL USUALLY WORK AGAIN.