I’m in a flight right now - C172 with G1000 NXi at 3,000 feet - and I notice the VAC gauge on the MFD is somewhat to the left of the green area. I believe this is measuring the vacuum pressure related to the gyro system. What is this telling me? Should I try to - and how would I - get this back into the green?
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I seem to recall it being affected by engine/prop RPM?
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Its the vacuum for air driven gyroscopic instruments indeed, on the G1000 I would assume this only applies to the stand-by instruments. Since its a vacuum gauge it doesn’t show pressure, rather the lack of pressure. There usually isn’t much you can do, it fluctuates a bit with engine RPM. Its supposed to rise, possibly into the red when engine RPM is low (e.g. idle). Given the pump is supplying sufficient suction, there is supposed to be a regulator maintaining a constant vacuum with varying altitude and engine RPM.
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I fly the same plane and my VAC gauge is below the green all the time, i guess its just a graphical bug/oversight as you would think they could easily have got it in the green all the time the engine is running, seems to make no difference at all.
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I don’t mean to disagree, but graphics are driven by the central processing unit. The CPU tells the graphics card what to do. I understand what you mean though.
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OK, then, I’ll make a note to check this on future flights and see if it varies at all. Based on these responses I did horse around with RPMs a little during the flight, but if the needle moved at all, it did only slightly.
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