A student recently installed a Garmin 430. It will not pick up a
nearby VOR on the ground, while his old 170B will. The needle comes
alive just after liftoff, but it does seem to have a lot of course
roughness.

His localizer also exhibits a lot of course roughness when far out on
the localizer, say, 15 miles. In visual conditions, I could see the
airport off to our left, but the needle was centered. Shortly
thereafter,the needle moved left and he corrected to what appeared to
be truly the extended centerline of the runway.

I'm not comfortable with this aircraft in IMC until I'm assured the
course guidance is rock solid. Any thoughts as to what might be
causing these indications?

In article >,
Greg Esres > wrote:

> A student recently installed a Garmin 430. It will not pick up a
> nearby VOR on the ground, while his old 170B will.

Say what you want about the miracle of modern electronics, but the
KX-170 was a hell of a fine radio.

> The needle comes
> alive just after liftoff, but it does seem to have a lot of course
> roughness.
>
> His localizer also exhibits a lot of course roughness when far out on
> the localizer, say, 15 miles. In visual conditions, I could see the
> airport off to our left, but the needle was centered. Shortly
> thereafter,the needle moved left and he corrected to what appeared to
> be truly the extended centerline of the runway.
>
> I'm not comfortable with this aircraft in IMC until I'm assured the
> course guidance is rock solid. Any thoughts as to what might be
> causing these indications?

I'm going to guess the antenna. One of my club's CNX-80's had one of
the legs of the nav antenna (V-style on the vertical fin) fall off. It
exhibited similar symptoms to what you're describing, until the antenna
was repaired.

I agree with you about not taking it into IMC until it's fixed, for two
reasons. First is the obvious (you might get killed). Second is that I
think a lot of what an instructor teaches is attitude and judgment, and
you do that by demonstrating, not by talking.

Greg Esres ) wrote:

> I'm not comfortable with this aircraft in IMC until I'm assured the
> course guidance is rock solid. Any thoughts as to what might be
> causing these indications?

Greg, it may have to go back to Garmin for the fix. Last summer I
dropped off my GNS430 at Lancaster Avionics to have the software
upgraded. I also asked them to test the unit to ensure it was within
specs.

During the testing they discovered that the glidesope receiver was very
weak and recommended the unit be returned to Garmin for repair. I
agreed. Garmin validated that the problem existed and attempted to
correct it twice before it finally passed their internal quality
assurance testing group.



--
Peter

"Greg Esres" > wrote in message
...
>A student recently installed a Garmin 430. It will not pick up a
> nearby VOR on the ground, while his old 170B will. The needle comes
> alive just after liftoff, but it does seem to have a lot of course
> roughness.
>
> His localizer also exhibits a lot of course roughness when far out on
> the localizer, say, 15 miles. In visual conditions, I could see the
> airport off to our left, but the needle was centered. Shortly
> thereafter,the needle moved left and he corrected to what appeared to
> be truly the extended centerline of the runway.
>
> I'm not comfortable with this aircraft in IMC until I'm assured the
> course guidance is rock solid. Any thoughts as to what might be
> causing these indications?

Did the student's avionics shop replace the antenna and coax? It's not good
to go cheap on installs.

Karl

<<I'm going to guess the antenna. >>

That's sorta my guess, but I'm fuzzy about all the links in the chain
from the antenna to the little knob that I turn. ;-)

To top it off, the 170B has started acting flaky too.

Thanks!

<<During the testing they discovered that the glidesope receiver was
very weak and recommended the unit be returned to Garmin for repair.>>

I hope not...the unit already had to be replaced due to a blown
transformer (?) that made everything go dark, just a week after the
purchase.

The glide slope seems to work fine, but possibly we have a similar
cause, just different symptom.

Thanks!

<<Did the student's avionics shop replace the antenna and coax? It's
not good to go cheap on installs.>>

I don't know. He got it done before I ever got in the airplane. I
guess you're suggesting that this would have been a good idea?

I'll ask.

Thanks!

Try swapping the antenna coax from one radio to the other.

Mike
MU-2

"Greg Esres" > wrote in message
...
>A student recently installed a Garmin 430. It will not pick up a
> nearby VOR on the ground, while his old 170B will. The needle comes
> alive just after liftoff, but it does seem to have a lot of course
> roughness.
>
> His localizer also exhibits a lot of course roughness when far out on
> the localizer, say, 15 miles. In visual conditions, I could see the
> airport off to our left, but the needle was centered. Shortly
> thereafter,the needle moved left and he corrected to what appeared to
> be truly the extended centerline of the runway.
>
> I'm not comfortable with this aircraft in IMC until I'm assured the
> course guidance is rock solid. Any thoughts as to what might be
> causing these indications?
>
>

This isn't normal behavior for a 430. Hard to say what the problem is,
but the cable and antenna are critical parts of the chain.