If you are experiencing tuning and/or garbled transmitter problems with your KHF-950 system, you may have some outstanding Service Bulletins that should be installed.
Within the last three years, I've reviewed several aircraft maintenance records for various aircraft and noted missing entries regarding non-OEM-related equipment. It’s not the major maintenance and inspections that are missing from the logbooks, but rather the small unknown inspections and ongoing required programs that remain outstanding.
Our experience has found that moisture was causing corrosion leading to the failure of the Bendix GCU.
Although Service Bulletin SBF2-12-001 is not mandatory, API strongly recommends compliance during the next maintenance event in which the ailerons are removed from the aircraft.
If you have the centrifugal compressor impeller with the designated part and serial number, accomplish the initial borescope inspection at the next designated airframe inspection.
Having the right information about the circumstances surrounding a squawk can save your tech rep many hours of troubleshooting time and yourself a considerable amount of money.