HSI and GPS doesn't match

[Parmesan]

Hello!

I recently bought the beechcraft duchess and I'm wondering about the HSI. It seems to be wandering, or something else, since all my holdings/approaches, after a certain time does not add up.

The GPS says my track is something which makes no sense. After restart the problem seems to restore itself. I read the POH and says the HSI should be a fixed card. Am I doing something wrong? Is HSI "fail safe" and should stay the same way throughout the flight, considering no settings have been changed?

I attached a picture of the HSI, which indicates a heading of 199 degrees, however, the GPS indicates a track of 189 which is the correct bearing at my current position. The HSI indicated 189 before  take-off and has rotated through 10 degrees during flight, now showing 199.
Is there any way to solve this problem?

Thanks in advance!

Attaching a picture of the GPS and HSI so you can see how the numbers don't match

[Ubbi]

Hi,

I´m from Germany.. so may be i dont understand your question right...

At the screenshot the GPS ist not coupled to the HSI.

So the HSI will show you whatever you have dialed in at your NAV-Radio.

To couple the GPS to your HSI you have to press the CDI knob (the left one out of the five at the bottom of the GPS). Then the white "VLOC" at the GPS-Display will change to GPS and your HSI will finally show you what it gets from the GPS.

 

I hope i could help you...

 

Regards,

 

Philip

[Parmesan]

Hi,

I´m from Germany.. so may be i dont understand your question right...

At the screenshot the GPS ist not coupled to the HSI.

So the HSI will show you whatever you have dialed in at your NAV-Radio.

To couple the GPS to your HSI you have to press the CDI knob (the left one out of the five at the bottom of the GPS). Then the white "VLOC" at the GPS-Display will change to GPS and your HSI will finally show you what it gets from the GPS.

 

I hope i could help you...

 

Regards,

 

Philip

 

Thank you for answering, Philip!

Although, you seem to have misunderstood my problem, or I'm bad in explaining my problem

 

The HSI CDI is fine. I tune the CDI to the navaid and radial I want to follow and I'm aware of how to set the CDI correctly.

However, the Heading of the HSI does not match the GPS. This is made in zero-wind conditions where the track and heading are supposed to be identical.

At the beginning of the flight, the heading and track match (zero-wind) correctly. After I have been flying for some time, the HSI seems to wander, i.e. the heading does not match the track of the GPS (still zero-wind).

The difference can be quite large, which makes instrument flying difficult.

Let's say I want to follow a track of 090° in zero-wind conditions - I need to use heading of 080° or maybe even 070° in order to maintain the track - the difference is 10-20° off, which is not supposed to be.

 

Best regards,

 

David

[Goran_M]

That's quite a big difference, and one I haven't noticed.  Give me a few days to have a look (I've been up to my armpits in Saab and DC-3 updates lately) and I'll run some tests.

 

[Parmesan]

That's quite a big difference, and one I haven't noticed.  Give me a few days to have a look (I've been up to my armpits in Saab and DC-3 updates lately) and I'll run some tests.

 

Sounds great!