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KI256 problems, replacement options, etc

If the spinning noise is quiet when the engine stops then it is likely related to dirt/vacum issues than mechanical problems from the previous hard landings :)

The formers will be hard to reproduce and fix on the ground

Paris/Essex, France/UK, United Kingdom

The Aerovonics AV30 with their APA10 adaptor is supposed to emulate a KI256.

The catch? It is uncertified


And the other catch is that the APA10 doesn’t exist

Administrator
Shoreham EGKA, United Kingdom

The latest claim from the US is that the KI300 and the KA310 are both certified and can be used to replace a KI256.

The original announcement was in 2015

The price is much less than a KI256 but a lot more than getting a KI256 overhauled

and what do you do about redundancy? You still need a vacuum AI somewhere, unless you have a lot of electrical redundancy.

Administrator
Shoreham EGKA, United Kingdom

Is that true for N-reg? I flew a C172 recently that has two G5’s and no vacuum system. The electric system is still the standard single battery single alternator concept. I don’t know about the installed backup battery capability however.
So if the KI300 has no backup battery, I agree. Otherwise they should have a similar path.

Last Edited by TobiBS at 25 Jul 08:05
P19 EDFE EDVE EDDS

Yes, it is, certainly for IFR.

One can meet the requirement with a backup battery, which can be quite a short duration one so you will likely not be able to complete the flight unless you get out of IMC. I would never accept a solution which means, basically, death after 30 mins unless you can get out the cloud.

Various previous threads on the backup requirement. I believe @ncyankee is the expert on this.

Entering e.g.

vacuum AND battery AND backup

into the search box digs out some info.

FAR23.1311 refers and I have some info here.

It would be astonishing if the KI300 had no backup battery connection. I have no installation manuals for any of this stuff.

However: from the HBK website: Its internal battery eliminates the need for a vacuum gyro and provides 2 hours of standby performance.

Administrator
Shoreham EGKA, United Kingdom

As pointed out by @sir_percy above, the above G5 + GAD29B route is no good. It is one which a number of people have gone down, only to discover that they or their installer didn’t understand the details. The G5 cannot replace a KI256 or any other King AI for pitch/roll source purposes.

I do have a little data point, from a pilot in the US. Unfortunately this is not an STCd solution (would need a Field Approval). The Castleberry 900-23EVPK electric AI (also sometimes called KI254) can drive a King autopilot. With some AP models there is a roll stability problem which requires a 1:2 step-up transformer in the excitation signal to the AI, and a Vigortronix VTX-101-006 audio txf, wired as an auto-transformer, solved that.

The 900-23EVPK is a full plug-compatible KI256 replacement including a flight director, and Castleberry test them in the same fixture which they used for testing the KI256 when they made them for Honeywell some years ago. But as often the reality is different and some King autopilots don’t use the 400Hz excitation signal but use something different…

I think that, as of today, the KI300 is the best way forward to replace a KI256. However, I would give it time because HBK have a long history of dropping products which aren’t selling, and nearly everything they have introduced in the last 15 years or so has failed in the market…

Administrator
Shoreham EGKA, United Kingdom

I’ll use this thread instead of starting a new one;

During straight & level flight (AP KFC150 in ALT & HDG) attitude indicator (KI256) slowly starts to pitch down to -15 degrees. AP reacts with pitch up trim and acft starts to climb. After a couple of ap on/off cycles the pitch up becomes rather agressive. Nothing to do but to handfly the remainder of the flight.

The next flight, same problem

The bank indication is spot on, so only the pitch axis is way off.

I guess I have a bearing problem. Is this something that can be repaired (<1K $) ? I’d like to upgrade to glass, but now is not the time. And I’ll need the KI256 for the AP…

EBST, Belgium

Three similar threads merged.

It is probably a bearing problem. I have used various European repair shops for these but none were satisfactory. The last one, in the UK, took 6 months and the unit came back without any paperwork (they had a “deal” with another company to use their “part 145 paper printer” but by the time they finished the job the arrangement has ended) I prefer to send mine to Castleberry in Texas, US.

You can pick these up fairly cheaply on US Ebay now (because they are being replaced by various “glass” options) but that won’t be any good for an EASA-reg plane.

This thread may also be of interest.

Best thing is to buy a spare KI256 and keep it on the shelf. Then you can swap them and sort out the old one at your leisure.

Administrator
Shoreham EGKA, United Kingdom

Here

Does this mean the N-flyers can buy and install this AI ?

EBST, Belgium

Yes.

As posted above, the KI300 is a re-branded Sandia SAI 340, so perhaps it has a higher immunity from being dropped than other HBK products

However, you also need the KA310.

Administrator
Shoreham EGKA, United Kingdom
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