Tommy

IFD not talking to KI256?

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Looking for some advice from anyone who has Avidyne 440 / 540 plus KFC 200:

 

So I took my plane out for a quick VOR departure and RNAV approach to land today. Wind calm. 

With VOR, IFD indicates VLOC. The CDI on my HSI is giving the correct deviation when the course heading is set correctly but when the AP is engaged to NAV / CPLD mode, it turns the plane to exactly 30 degree left of the course and stays there even when the deviation clearly was on the right. 

With RNAV approach, IFD indicates GPS -> LNAV +V. The CDI is again giving the correct deviation when the course heading is set correctly but when the AP is engaged to APPR / Arm mode, nothing happens. The FD isn't doing anything at all and doesn't fly from one way point to the next. 

Before I ring my avionics shop, I just want to make sure that I have the right A/P settings. One thing I didn't do was to "Activate Approach" when I was doing the RNAV approach today. Would that have made an difference?

Thanks everyone! 

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3 hours ago, Tommy said:

Looking for some advice from anyone who has Avidyne 440 / 540 plus KFC 200:

One thing I didn't do was to "Activate Approach" when I was doing the RNAV approach today. Would that have made an difference?

Thanks everyone! 

Sorry, don't know anything about the IFDs, but it you activate any leg of an approach or go direct to any point on the approach, you have activated the approach.

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7 hours ago, donkaye said:

Sorry, don't know anything about the IFDs, but it you activate any leg of an approach or go direct to any point on the approach, you have activated the approach.

I thought as much since the IFD switched to GPS-> LNAV+V automatically. But when you engage NAV or APPR mode, does the AP track? 

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2 hours ago, Tommy said:

I thought as much since the IFD switched to GPS-> LNAV+V automatically. But when you engage NAV or APPR mode, does the AP track? 

If it's wired property it certainly should.

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So it turns out to be my lateral axis board defect on my KFC computer.

The shop replaced it with their own board and it seems like the situation is much better. It steers the plane pretty much spot on en route.

However it's far from perfect. I shot an RNAV approach and I activated NAV / CPLD mode then activated the leg when prompted by IFD440. Then set the CDI to the course heading. The CDI showed the deviation correctly and FD commanded the turn but it was so slow (bank angle of 10 degree or less) that I flew right pass the magenta line for almost 1 or 2 miles! Can't possibly imagine doing this in IMC.

I can possibly get around this by activating the leg and turning the CDI course a lot earlier but then I will still be flying a big arc that will take me 1 or 2 miles away from the intended course. I don't think my vertical / lateral separation from the ground can be guaranteed! 

Am I doing something wrong? Or does this replacement board need tweaking? Or a hands-free RNAV approach is not possible with IFD440 + KFC200 (Gosh, I hope not!!) ? 

Thanks guys! 

 

 

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12 minutes ago, Tommy said:

So it turns out to be my lateral axis board defect on my KFC computer.

The shop replaced it with their own board and it seems like the situation is much better. It steers the plane pretty much spot on en route.

However it's far from perfect. I shot an RNAV approach and I activated NAV / CPLD mode then activated the leg when prompted by IFD440. Then set the CDI to the course heading. The CDI showed the deviation correctly and FD commanded the turn but it was so slow (bank angle of 10 degree or less) that I flew right pass the magenta line for almost 1 or 2 miles! Can't possibly imagine doing this in IMC.

I can possibly get around this by activating the leg and turning the CDI course a lot earlier but then I will still be flying a big arc that will take me 1 or 2 miles away from the intended course. I don't think my vertical / lateral separation from the ground can be guaranteed! 

Am I doing something wrong? Or does this replacement board need tweaking? Or a hands-free RNAV approach is not possible with IFD440 + KFC200 (Gosh, I hope not!!) ? 

Thanks guys! 

 

 

It all depends on who has worked on your KFC200 in the past. Shops that don't specialize in and aren't experts in King autopilots usually make a problem much worse. It is worth what they charge to only have someone that intimately knows these devices and has the proper diagnostic boxes work on them. The KFC200 is actually a very good autopilot that flies on rails if it's working and adjusted properly.

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It sounds like you were in a nav track mode where it limits the banks to 10 deg of correction.  This is completely normal for nav track mode.   The computer was designed to compute intercept angles for proper nav track.  If you refer to that attached file page 40 it will outline how to set up the system for a RNAV intercept/capture.  As long as the computer has the proper setup for intercept/capture you should not experience the shallow bank limit. 

KFC 200 Pilot Guide.pdf

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Welcome aboard Jake!

It is great to have the Bevan-Rabell team on board!

Best regards,

-a-

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@Tommy,

 

  I have the IFD 540 / KFC200 combination with GPSS added.  When I'm intercepting the final approach course and within 1nm of that course, I switch the auto-pilot to Apprch mode, it will usually arm then couple within .5nm of the FAC and the turn will be whatever angle needed to intercept.

 

Ron

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6 hours ago, Marcopolo said:

@Tommy,

 

  I have the IFD 540 / KFC200 combination with GPSS added.  When I'm intercepting the final approach course and within 1nm of that course, I switch the auto-pilot to Apprch mode, it will usually arm then couple within .5nm of the FAC and the turn will be whatever angle needed to intercept.

 

Ron

Good point. I think I did have it in Appr / Arm mode. 

Where do you normally switch from Nav to Appro mode, Ron?

Thanks 

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2 hours ago, Tommy said:

Where do you normally switch from Nav to Appro mode, Ron?

  I usually make that switch as I approach the final approach course either within a half mile or so of intercept(less than half scale deflection with needle moving in) if on VTF or with no procedure turn, or the last leg of the procedure turn if flying the full approach.

 

Ron

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