GNS 530w & KFC 150

[rreed1963]

Hello,  this is my first post here and If this has been covered, I am sorry, but could not find my exact problem..

I just traded my F model in on a 1985 K model, with a KFC 150 with VS and ALT preselect and a 530W comm 1 and a 430W comm 2

Flying an ILS approach the KFC 150 works good, a little left of center but very good and captures the glide slope perfectly. 

However, on an RNAV approach it will track the inbound course fine, and the 530 will switch to LPV mode, but the autopilot will not catch the "glide slope"

The HSI indicates that I am below the glide path correctly when first starting the approach but will not catch it and fly it.

Any help will be appreaciated

Thanks

Richard

[Marauder]

Richard - there may be a distance requirement before the LPV glide slope can be captured. This may be lateral as well as distance from the glide slope intercept point. If you are on the "localizer" it should capture if you are at the correct altitude on the approach.

Have you tried the 430W to see what it does?

[rreed1963]

Thanks for the reply.   I tried to intercept from severial differnet alltitudes, mostly between 100 and 400 feet below.  Upon crossing the FAF, the 530 shows LPV but and the HSI indicates below glide slope, but the autopilot does not grab it.  I do not have a way to set the 430 up to the autopilot. 

[kortopates]

No indication of a failure from what I am understanding. You have to intercept the GS before the AP will capture. 100' to 400' below is not intercepting it. For example, fly down to the altitude of GS intercept at the FAF well in advance of getting to the FAF; preferably with enough time to be flying level in NAV or HDG mode and with ALT engaged to hold altitude at GS altitude intercept height. Once stable engage APR mode, once you are within 2-3 dots laterally APR mode will engage. As you intercept the GS, ideally exactly at the FAF so you can verify by cross checking altimeter altitude to GS intercept (GS needle centered), then the GS will arm and continue to follow it. But you have to intercept it before it will arm. An important reason for this is that you don't want the AP to fly up 400' to capture it right when APR mode engages laterally. You have to intercept it first. If you cross through the GS (GS needle centered) and the AP GS does not arm/engage then there is something wrong with the AP.

Flying a "little left of center" though could be a concern. In APR mode it should be right on.

Sent from my iPad using Tapatalk

[M016576]

The left of center problem can be fixed with one of the pots on the faceplate. That's easily accomplished with a very small flathead screwdriver

Just to make sure I'm understanding you- you set APP and ALT prior to glideslope intercept. The airplane tracks the course fine, but when you fly through the glideslope, the airplane doesn't tip over and commence the approach?

If that's the case, then...

The glideslope capture is a specific signal from the GPS to the autopilot. Sounds like you've lost that signal somewhere (probably a broken wire between the 530 and A/P computer, or the connector has come loose). You can find the KFC150 installation manual on Google- that will tell you the specific wire / pinout to look at to see if something obvious sticks out.

Does the autopilot track the ILS glideslope through the 530, or is your ILS coming from somewhere else (KNS80)? If it is through the 530, then you may need to call up Autopilots Central and ask them...

[rreed1963]

The left of center problem can be fixed with one of the pots on the faceplate. That's easily accomplished with a very small flathead screwdriver

Just to make sure I'm understanding you- you set APP and ALT prior to glideslope intercept. The airplane tracks the course fine, but when you fly through the glideslope, the airplane doesn't tip over and commence the approach?

If that's the case, then...

The glideslope capture is a specific signal from the GPS to the autopilot. Sounds like you've lost that signal somewhere (probably a broken wire between the 530 and A/P computer, or the connector has come loose). You can find the KFC150 installation manual on Google- that will tell you the specific wire / pinout to look at to see if something obvious sticks out.

Does the autopilot track the ILS glideslope through the 530, or is your ILS coming from somewhere else (KNS80)? If it is through the 530, then you may need to call up Autopilots Central and ask them...

Yes you are correct.  When I cross the GS in an RNAV approach the the plane doesnt grab it.  and yes, the ILS is through the 530  I guess it may be time for an appointment at the avionics shop.  thanks for your help

[laytonl]

My KAP150 and 530w will work fine on RNAV approaches provided I'm at appropriate altitude at the last fix prior to the FAF. I believe the 530w sends a signal to the KAP150 about 2-3 miles from the FAF to activate the GS.

A good example is the RNAV 3 into MRN. The GS will only capture if I'm at exactly 3,700' at CETAM, which is the fix prior to the FAF.

Same thing on the RNAV 21 into MRN. The GS capture occurs at ZAGOK only if I'm exactly on altitude.

Lee

[carusoam]

As Lee points out...

It is worth checking the rules of engagement for your system...

The plane needs to be pretty far out, within an altitude range that works, to automatically engage...

Good news, reading the extensive books may save a few bucks....?

If you've done that already...there is still hope in cleaning and resetting connections.

Best regards,

-a-

[rreed1963]

ok, I finally have the glide slope working properly.  Yes, it was a wire that was not broken, it was never installed.  the avionics shop got that problem fixed.  However, I am still having an issue with the autopilot flying left of course.  On an ILS approach, the HSI will show a dot and a half off course to the left. and it is exactly correct.  I am that far off to the left.  It would take you to the runway  but just to the left side, in the dirt.  My shop says i need the KFC150 overhauled or they want to sell me an avodyne and say that would fix the problem. Let me know what you think..  I really dont want to spend the money on sending the autopilot off for repair if I dont have to.  Sounds like it should be an easy adjustment

[rreed1963]

^{MO16576 said the left of center problem could be fixed with one of the pots on the faceplate.  What pots?  I need more understanding of this problem}

[WilliamR]

On the face of the KFC-150 there are small holes.  Three, going from memory.  Each hole goes to a "pot" in the unit.  A long avionics screw driver is needed to insert in the face of the KFC-150 and reach the respective pot. Each pot does something different including left or right of course and how closely the flight director syncs with the "airplane" in the attitude indicator.

 

Not uncommon for these to be off.  Care must be taken to not knock over the pots.  It's easy to do.  Hope that helps.

 

William

M20K-252, KFC-150 tied to G530.