In my manual (Century NSD360A, 10-01-99, 68S85), the following appears in a paragraph on page 4:
… In slaved versions, the slaving meter should oscillate about a 45 degree point to show that the slaving circuits are accomplishing their function. Should the needle remain motionless, vertical, or horizontal for an extended period (two minutes) in level flight, the heading should be manually set so that the slaving meter is at the 45 degree point and then observe the performance of the heading card. If slaving difficulties are encountered, set the slaving mode switch to SL#2 or free gyro. In free gyro mode, the instrument must be periodically reset to manually counteract the effects of gyro precession.
The grammar may not be the best (they have a tendency to often split infinitives!), but hopefully this resolves the apparent contradiction between what Dave and I said.
Mike & Dave,
Can either of you point to any documentation (on the web or hard copy) that describes this?
Unfortunately, you’ve sort of contradicted each other. (Dave says if it’s pointed at a 45 degree angle [presumably stationary at this position], all is good. Mike says if it’s stationary, watch out!)
The only “mention” I see of this in the Century manual is a little note pointing out that this line is the slaving meter, but doesn’t describe what it means. But I notice all the pictures of the HSIs in the manual have the line at a 45 degree angle.