VOR / HSI problem

[Mistake Not...]

During a VOR check discovered the one in the HSI is off 10 degrees. This is driven by the VOR receiver in the Garmin 430. Using the 430 in "gps" mode, it appears to be fine.

Which is more likely.. a Garmin problem or an HSI problem? I'd like to understand more about it before talking to the avionics tech. Not that I can do much, but I hate just dropping the plane off with a blank check.

 

[wsuffa]

Old 430 or -W version?

I had a similar problem that turned into full-peg deviation that turned out to be a problem in the 430. Did the upgrade to the -W version as Garmin isn't repairing the old 430s.

 

[Mistake Not...]

crap. It's a 430W. It's old though.

 

[wsuffa]

It could be something else, like a bad ground. Or it could be the circuitry in the VOR side of the 430. When mine went, it was both GPS and VoR that were affected. How is it on ILS?

 

[Mistake Not...]

That's the weird thing... it worked on the ILS. I'm flying with an instructor tonight and we're going to try some stuff. I'll be sure to check the ILS as well and see if it still works (last time I remember checking it was before annual).

 

[flyingron]

Which HSI? Some of the modern electronic ones take an Arinc 429 digital signal from the 430, others use the old style HSI resolver.

Despite similar presentation, LOC and VOR (and for that matter VOR) signals are handled differently. The OBS(course indicator) setting matters not to LOC or GPS but is important in the VOR handling. The 430W does have a selected course calibration adjustment. See 5.3.10 of the installation manual.

 

[Mistake Not...]

I'm not sure. I left to go flying before I saw this yesterday so I didn't check. It's on an '81 mooney with the KFC 200 autopilot.

Ah. The calibration function looks like it might do it. It's consistently off 10 degrees (regardless of radial selected), so maybe I'll get by relatively cheaply on this.

Thanks.

Which HSI? Some of the modern electronic ones take an Arinc 429 digital signal from the 430, others use the old style HSI resolver.

Despite similar presentation, LOC and VOR (and for that matter VOR) signals are handled differently. The OBS(course indicator) setting matters not to LOC or GPS but is important in the VOR handling. The 430W does have a selected course calibration adjustment. See 5.3.10 of the installation manual.