A36 Heading in Free mode
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My Compass heading and HSI heading are off by 10°, most of the time, so I place it in Free mode and adjust my HSI to match the compass but when I do that and want autopilot to follow my heading, it is not aligned. For example, if I place my heading bug at 190° and in Free mode while in autopilot, the plane flies a heading of 196°. Is this normal behavior?
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If you have windshield heat on, or some other high electrical load circuits, then your magnetic compass will be offset by several degrees depending on intensity of the electromagnetic fields generated by those circuits. The windshield heat is typically the most obvious and significant cause.
This models real world behavior and is why many aircraft have reminder placards that state magnetic compass should not be used when windshield heat is in use as well (though I don’t recall if the Duke/Baron/Bonanza include that placard).
There are some notes on this effect in the manual and you can experiment with different circuits to see the effect (toggle your windshield heat, starter, or pitot heat and observe the compass). You should generally avoid slewing your HSI to match the compass.
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If you have windshield heat on, or some other high electrical load circuits, then your magnetic compass will be offset by several degrees depending on intensity of the electromagnetic fields generated by those circuits. The windshield heat is typically the most obvious and significant cause.
This models real world behavior and is why many aircraft have reminder placards that state magnetic compass should not be used when windshield heat is in use as well (though I don’t recall if the Duke/Baron/Bonanza include that placard).
There are some notes on this effect in the manual and you can experiment with different circuits to see the effect (toggle your windshield heat, starter, or pitot heat and observe the compass). You should generally avoid slewing your HSI to match the compass.
@Iconography Yes, I am aware of the windshield heat causing problems with the Compass and I didn't have the windshield heat on when observing this. I didn't have any GPS unit installed just the radios but I did have the weather radar on. I will toggle this on and off next time to see if this makes an impact. Thanks for the response.
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