HSI jumps 55 degrees when Slave is engaged

Misty74Misty74
in General Discussion
Hi everyone,
I've not been able to find any information on the possible cause and am hoping someone might be able to help out..
We have a 74 Arrow II with a King KA51A compass slave...
We are able to line up the HSI with the wet compass but the moment we engage the slave, the HSI turns 55 degrees to the left.
Any suggestions on where to look for the cause?
It may just be a coincedence but the problem occurred on the first flight after the annual was completed.
Is is possible they may have disconnected something?

Thanks in advance for your help!!
Graham

Comments

  • Bob HBob H
    Hi flyboyg,
    Here's a comprehensive response to your question from one of my tech buddies to your issue with the KCS-55A HSI system:

    " Several possibilities here. The system only does it while in slave mode. That tells me it involves the KA-51A/KMT-112. The KMT-112 was either
    loosened and readjusted, either on purpose or for maintenance of surrounding areas. It could also have some new ferrous metal installed near
    the KMT-112 like a new antenna or grounding plate for another system. Last idea is either high current wires (Beacon, strobe, power supplies),
    or COMM Coaxes are laid or are running parallel to the KMT-112 wires. Or the KA-51A adjustment (N,S,E,W) got moved."

    If the problem first occurred after your annual, it's a good bet that this is the source of the problem and a very good time to remind all pilots that the most dangerous time to fly your aircraft is just after significant maintenance or modification! I would go back to your maintenance shop and have this discussion.
    Good luck! Bob Hart www.AvionixHelp.com
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