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King KI256 Issue


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To do anything useful in the form of troubleshooting I suggest pulling out the BK KFC150 AFMS which should be in your POH or at least on board or you aren't legal. If the AFMS their is a preflight test procedure. You can't run this test unless the engine is running unless you have electric standby vacuum; if so turn that one and let the AI stabilize and then begin the pre-flight test. That should help highlight the issue(s). It really does look like the AI is Tango Uniform but without doing the basic pre-flight test who knows what's really going on. 

Also keep in mind even if it is working correctly you need to use the CWS button the yoke to use the altitude functions properly. That goes for maintaining pitch with the Altitude button off and for maintaining altitude with the Altitude button light on. Its not enough to just push Trim down and trim up since you may not be holding it down long enough if it was really far off. However, I don't think that's your problem but the CWS butto is the proper way to test this in flight. Trim up and down buttons on the AP computer should only be used for small corrections; not a 10 degree correction.  

As for whether glass would solve the problem that would of course depend on whether the issue is limited to the KI-256 and if you also purchased the additional autopilot interface for the glass AI, such as the EA-100 for the Aspen or GAD-43 for the Garmin. i.e. more cost than just the glass AI. But you know once you start down that path you can't stop and you'll still need a backup AI for what ever glass option you pick. The truth is all of us glass converts just use the failing AI or HSI as an excuse to do what we've been wanting to do for a while. :)

Seems like your new 231 came with a lot of issues? Insufficient pre-buy or maybe they were known?  

 

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Just now, Kevin Pare said:

Well, happy to report I went for 2 flights today. Both times it worked perfectly. Maybe it is a vacuum issue. I do have an elec vacuum so I'll do some more testing.

When mine went belly it up it was a very gradual thing. Would fly fine and then get off 5 degrees, 20 minutes later it was normal again. The bearings go bad in them. It sounds like it is on its way out. Do you have a backup AI?

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11 hours ago, gsengle said:

I dream of going all electric. I'm in a FIKI Ovation, already have all the dual electrical gear. Just waiting for a good AI option...

The 252 is finally in the avionics shop. It's getting a single Aspen panel, and I'll likely remove as much of the vacuum system as possible, while still retaining my vacuum speed breaks. I'm right now trying to decide on a suitable electric AI option to back up the Aspen.

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13 hours ago, Zwaustin said:

When mine went belly it up it was a very gradual thing. Would fly fine and then get off 5 degrees, 20 minutes later it was normal again. The bearings go bad in them. It sounds like it is on its way out. Do you have a backup AI?

Yes, i have an electric AI, maybe they have known about this issue for some time.

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8 hours ago, Andy95W said:

Paul- does this mean that (hopefully) your fuel tank issues are resolved?

Yes, we have an approved fix and are working through it. The DER prescribed a doubler to cover the spot after the corrosion was all cleaned out. The doubler is only about 4" long. It's taking awhile with all the approvals and inspections, but I think we'll be done in another week.

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21 hours ago, gsengle said:

I dream of going all electric. I'm in a FIKI Ovation, already have all the dual electrical gear. Just waiting for a good AI option...

In my M20R the Moritz vacuum gauge is covered over inside with flat black tape.

I have the G500 as primary AI with L-3 ESI-2000 secondary and FS210 as tertiary.   In murky IMC (such as coming home from Tulsa this past weekend)  I have all three displayed (FS210 presents its AHRS on iPad and Garmin 796).    The newer ESI-500 looks even nicer and is cheaper than the earlier version.  

What are you waiting for?  Mere cash?   If you leave it to your kids they'll probably just squander it on something not even aviation related. 

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2 hours ago, Kevin Pare said:

Yes, i have an electric AI, maybe they have known about this issue for some time.

Most Ks of this vintage have the electric backup AI. Mine does, as does most I have seen around here.  I believe vacuum pump failure has been an issue or concern with Mooney at this time.

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In my M20R the Moritz vacuum gauge is covered over inside with flat black tape.
I have the G500 as primary AI with L-3 ESI-2000 secondary and FS210 as tertiary.   In murky IMC (such as coming home from Tulsa this past weekend)  I have all three displayed (FS210 presents its AHRS on iPad and Garmin 796).    The newer ESI-500 looks even nicer and is cheaper than the earlier version.  
What are you waiting for?  Mere cash?   If you leave it to your kids they'll probably just squander it on something not even aviation related. 


Waiting for better options! But still wanna see a photo of your panel :)


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3 hours ago, Kevin Pare said:

Yes, i have an electric AI, maybe they have known about this issue for some time.

Glad to hear. A backup is a must if flying hard IFR in my opinion. The KI256 should give you about 800hrs but when it goes or shows signs of going it cannot be trusted in IMC. Invest in the overhaul if using it as a primary or if you have it driving your AP. My K model had the Aspen as primary then the KI256 as a backup AI along with AP driver and had a back up electric standby vacuum pump should the primary pump fail. Redundancy is good!

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The 252 is finally in the avionics shop. It's getting a single Aspen panel, and I'll likely remove as much of the vacuum system as possible, while still retaining my vacuum speed breaks. I'm right now trying to decide on a suitable electric AI option to back up the Aspen.


You have two options. The Sandia Quattro SAI 340 can be installed with FAA approvals or the L-3 ESI 500 that needs to approvals. I am in the process of having the L-3 unit installed.

Unfortunately the G5 is not approved.


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3 hours ago, Marauder said:



Unfortunately the G5 is not approved.


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This is the case for the g500 but you are gtg with the aspen unless you have all three screens. It's certified for primary position if it's not replacing a FD or the T&B location.  It actually makes a perfect backup to the aspen because it will continue working after plugged static/airspeed ports.  That and a completely different software/hardware design w/ a inexpensive battery backup make for a great setup. 

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On 3/26/2017 at 11:17 PM, gsxrpilot said:

The 252 is finally in the avionics shop. It's getting a single Aspen panel, and I'll likely remove as much of the vacuum system as possible, while still retaining my vacuum speed breaks. I'm right now trying to decide on a suitable electric AI option to back up the Aspen.

That is the same issue I have with starting down the "glass" road - do I pull perfectly good speed brakes to completely eliminate vacuum and spend the AMUs to put in electric or what? My goal is to get out of the vacuum game, but until I am willing to either give up the speed brakes or replace something currently working, I am on hold.

At least until the HSI goes Tango Uniform. Then the checkbook comes out.

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14 minutes ago, Oldguy said:

That is the same issue I have with starting down the "glass" road - do I pull perfectly good speed brakes to completely eliminate vacuum and spend the AMUs to put in electric or what? My goal is to get out of the vacuum game, but until I am willing to either give up the speed brakes or replace something currently working, I am on hold.

At least until the HSI goes Tango Uniform. Then the checkbook comes out.

My thoughts on this have gone round and round a few times.  Where I've settled for now is by removing all the vacuum dependent instruments, if the vacuum pump goes out, I've only lost speed brakes and nothing critical. It also allowed me to remove the standby electric vacuum pump in the tail. It was quite heavy and will give me some useful load back. I don't think you have the second pump in the J.

I'll still have the engine driven pump up front, but it's only hooked to the speed brakes and nothing else. The only benefit of removing it would be a further weight savings. It's no longer a critical component in the airplane.

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22 hours ago, Godfather said:

This is the case for the g500 but you are gtg with the aspen unless you have all three screens. It's certified for primary position if it's not replacing a FD or the T&B location.  It actually makes a perfect backup to the aspen because it will continue working after plugged static/airspeed ports.  That and a completely different software/hardware design w/ a inexpensive battery backup make for a great setup. 

Unfortunately the G5 cannot serve as a backup to the Aspen. Trek Lawler from Garmin clarified this in December with the post below:

58daba68d3719_G5asBackup.thumb.JPG.03daa82b8095c06d5656dc1d86fc1187.JPG

Trust me, I wish this were true and I could install a 2AMU solution instead of a 6AMU one.

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For garmin lawyers the legal install is to replace the turn coordinator. If that placement is meet you are gtg. The unit is certified as a primary AI replacement with the proper battery life etc. 

My guess is the software code is very similar to the g500...

Some large shops are still installing them with the g500 but I'd go with the L3 in that case to get rid of all the round gauges. 

The sad fact is garmin can't provide a backup for their flagship products, probably on purpose so they won't be blamed for an instrument failure crash.

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For garmin lawyers the legal install is to replace the turn coordinator. If that placement is meet you are gtg. The unit is certified as a primary AI replacement with the proper battery life etc. 
My guess is the software code is very similar to the g500...
Some large shops are still installing them with the g500 but I'd go with the L3 in that case to get rid of all the round gauges. 
The sad fact is garmin can't provide a backup for their flagship products, probably on purpose so they won't be blamed for an instrument failure crash.


We went through this with Trek and I followed up with Aspen. The problem is the unit is not TSOd to revert to a performance level of a primary AI in case of a pitot static failure. The pitot static system is used to augment the attitude correction for the AI. This is defined under the TSO. A TSO that Garmin has not elected to pursue and based on Trek's message won't. I don't blame them.

The market share of backup AIs required for the G500 and Aspen PFD installed based is relatively small compared to the installed base of mechanical AIs that this unit is authorized to replace. In addition, the Sandia and L-3 units can met this requirement and are TSOd as such. Ironic as it is, you can install a G5 by itself and be legal. But you can't install it as a backup. Gotta love the logic on that one.


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2 hours ago, gsxrpilot said:

My thoughts on this have gone round and round a few times.  Where I've settled for now is by removing all the vacuum dependent instruments, if the vacuum pump goes out, I've only lost speed brakes and nothing critical. It also allowed me to remove the standby electric vacuum pump in the tail. It was quite heavy and will give me some useful load back. I don't think you have the second pump in the J.

I'll still have the engine driven pump up front, but it's only hooked to the speed brakes and nothing else. The only benefit of removing it would be a further weight savings. It's no longer a critical component in the airplane.

Now that is a good thought. I was going for the all-or-none, but leaving the pump on the engine only for the speed brakes makes sense - especially $$ sense.

Yeah, I do have the backup vacuum in the tail of the J. It was installed before I bought her and I actually test it every few weeks. Hefty little bugger.

I assume you have pulled out the HSI and all of the associated periphery. How much UL will you gain by installing the Aspen and EA100 (assuming you require it)?

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29 minutes ago, Oldguy said:

I assume you have pulled out the HSI and all of the associated periphery. How much UL will you gain by installing the Aspen and EA100 (assuming you require it)?

Yep, I've pulled the a lot of stuff out. I've installed the Aspen and the EA100. While I'm excited to "go glass" I'm even more interested in the UL i can gain. The 252's are often UL challenged and so I'm going for every pound. I think with everything I'll get more than 20 lbs.

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  • 2 years later...

I’ll put it in this topic because it seems appropriate.

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 occurs.

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...

 

 

7D36B55A-5945-41C4-80D0-5EEC3E1B1C1D.jpeg

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