Menu Sign In Contact FAQ
Banner
Welcome to our forums

KI256 problems, replacement options, etc

The GI-275 and G5 both have built-in GPS receivers, so they can be used standalone, not connected to anything else. Yes, the GTX345 with built-in GPS could be used.

Thing is, you’d want a GPS source to drive the autopilot, and that means GNS or GTN, with Avidyne being a gray area. Some nav radios could also be used.

No idea on the cost, but as you well know, with avionics the cost of the device is usually half the battle, so I’d ballpark $10k and then I’d want a GI-275 HSI so I can have a backup.

By then we’re into Aspen territory, which brings us close to G3X, which is only a step away from G500, so all said and done, with a GFC500 (because why not, while we have it all apart) probably $100k. Or wait and see what Dynon comes up with ;-) Man, I like spending other people’s money! Can’t wait to see that panel!

tmo
EPKP - Kraków, Poland

It sounds like a GI275 just needs a GPS antenna then, and will emulate a KI256 straight off like that. Well, with some rewiring. The battery backup will have a limited life but I happen to have a backup alternator.

The other stuff belongs under TB20 autopilot options and currently there aren’t any which are worth looking at (there are the toys from Trio or Truetrak which don’t do ILS and half the other stuff needed for IFR, and the GFC500 is vapourware). My KFC225 works just fine and the KLN94, or any other navigator, old or new, can drive it just fine. In fact when I do install a modern navigator I will feed the two SN3500s with ARINC429 and the LH SN3500 contains a roll steering converter which will drive the KFC225 via analog, H and V, and do so transparently whether flying ILS or LPV.

Incidentally I wonder if the GI275 has actually been tested with a KFC225. I ask this because the KFC225 uses a slightly nonstandard LVDT excitation frequency and waveform – about 10V rms sine at 500Hz whereas the others use 430Hz square wave. Castleberry made an electric KI256 lookalike which doesn’t actually work with the KFC225 due to this, despite passing the factory test in the same fixture used to production test the KI256 (Castleberry used to make the KI256 for King, originally).

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

Incidentally I wonder if the GI275 has actually been tested with a KFC225. I ask this because the KFC225 uses a slightly nonstandard LVDT excitation frequency and waveform – about 10V rms sine at 500Hz whereas the others use 430Hz square wave.

The installation manual of the GI275 explains in great details how to configure and calibrate the KFC225 in order to get it work with the GI275 as AI and for the FD part. You could not go towards this level of details without having it fully tested. Garmin is far from being a “garage” company!

Also, the GI275 legacy autopilot interface is based on the GAD43 for the G600/G500. Many of these are in the field today.

Last Edited by ploucandco at 26 Oct 12:30
Ukraine

Peter wrote:

dentally I wonder if the GI275 has actually been tested with a KFC225. I ask this because the KFC225 uses a slightly nonstandard LVDT excitation frequency and waveform – about 10V rms sine at 500Hz whereas the others use 430Hz square wave.

I believe there are some Mooneys flying with the KFC225 and GI-275, as well as some Beechcraft planes. If you want, I can check for details.

tmo
EPKP - Kraków, Poland

The KFC225 works much better in conjunction with the GI275 than the prehistoric KI256, waveform difference notwithstanding.

T28
Switzerland

Which aircraft has this been tested on?

Administrator
Shoreham EGKA, United Kingdom

If you ask about practical hands-on UAT, Ovation & Bo F33.

Pretty sure Garmin did their homework as well.

T28
Switzerland

UAT?

Are there any actual user reports of GI275+KFC225?

Administrator
Shoreham EGKA, United Kingdom

UAT = user acceptance testing.

That means a test done by a system user. So yes, actual user reports.

T28
Switzerland
tmo
EPKP - Kraków, Poland
Sign in to add your message

Back to Top