KFC 150 porpoising

[gabez]

Hello, 

I am sure this topic has been discussed several times, my KFC 150 has started porpoising. the AI has been recently overhauled so I would eliminate that. The porpoising is not getting better but it is still very random. Nothing comes out when I push the static line drainage. 

How does the KFC hold Alt or manages pitch, is it wired into the static line? 

Thank you 

Gabe

Edited June 20, 2023 by gabez

[Pinecone]

My KAP-150 does this.  I hit the CWS button and it stops, sometimes for no long.

The other suggestion is to clean and lube the yoke tube.  Although some yoke balls are supposed to be used unlubricated.

 

[gabez]

28 minutes ago, Pinecone said:

My KAP-150 does this.  I hit the CWS button and it stops, sometimes for no long.

The other suggestion is to clean and lube the yoke tube.  Although some yoke balls are supposed to be used unlubricated.

 

thanks I will try that. I tried to pull the alt static air...but it didn't make a difference. 

[LANCECASPER]

6 hours ago, gabez said:

Hello, 

I am sure this topic has been discussed several times, my KFC 150 has started porpoising. the AI has been recently overhauled so I would eliminate that. The porpoising is not getting better but it is still very random. Nothing comes out when I push the static line drainage. 

How does the KFC hold Alt or manages pitch, is it wired into the static line? 

Thank you 

Gabe

Where is it getting it's attitude information from?  A KI-256 Attitude indicator, Aspen (EA100), G500 (GAD) or GI275?

[gabez]

11 minutes ago, LANCECASPER said:

Where is it getting it's attitude information from?  A KI-256 Attitude indicator, Aspen (EA100), G500 (GAD) or GI275?

sorry I meant altitude. When you press the altitude hold, is it reading the static line? 

[LANCECASPER]

19 minutes ago, gabez said:

sorry I meant altitude. When you press the altitude hold, is it reading the static line? 

If the attitude indicator has ever been changed out since 1984 when the autopilot was installed, the attitude indicator and autopilot should be re-aligned. When mine was changed out years ago I had the same symptoms until it was re-aligned.

[gabez]

2 minutes ago, LANCECASPER said:

If the attitude indicator has ever been changed out since 1984 when the autopilot was installed, the attitude indicator and autopilot should be re-aligned. When mine was changed out years ago I had the same symptoms until it was re-aligned.

Interesting, the AI KI256 is the original with the plane but it was overhauled about 2 months ago and then is when the problem started so I can see that. Let me check with my avionics guy to see if it is something he can do. 

Gabe

[LANCECASPER]

2 hours ago, gabez said:

Interesting, the AI KI256 is the original with the plane but it was overhauled about 2 months ago and then is when the problem started so I can see that. Let me check with my avionics guy to see if it is something he can do. 

Gabe

Bingo! It think it needs to be aligned with the kc192 computer. Whether this takes a KTS-150 break out box, which very few shops have anymore, I'm not sure.

[PT20J]

I believe it can be aligned on the bench using a fixture that holds the gyro if they have the gyro and the computer. At least that is what Steve at Executive Autopilots told me a few years ago. @Jake@BevanAviation should know.

[gabez]

oof I feel I am f.ed and I see an Aspen in my future. 

[Jake@BevanAviation]

Any time the attitude gyro is repaired or replaced, the system needs to be aligned to the attitude source.  This requires the KTS150 test set, you can make an adapter to run the KI256 with the flight computer to be aligned on the bench.  The KTS150 comes with harness to align it in the aircraft with the attitude gyro on a tilt stand.  

[gabez]

Just now, Jake@BevanAviation said:

Any time the attitude gyro is repaired or replaced, the system needs to be aligned to the attitude source.  This requires the KTS150 test set, you can make an adapter to run the KI256 with the flight computer to be aligned on the bench.  The KTS150 comes with harness to align it in the aircraft with the attitude gyro on a tilt stand.  

thank you sir. does anybody here happen to know a shop in the Bay Area/california that can do it?

 

[kortopates]

Sacramento Executive - Executive Autopilots. they’re the experts on the west coast and not far from you.


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[Pinecone]

6 hours ago, gabez said:

oof I feel I am f.ed and I see an Aspen in my future. 

My airplane, which sometimes porpoises has an Aspen. 

So that may not be a fix.   

[LANCECASPER]

9 hours ago, gabez said:

oof I feel I am f.ed and I see an Aspen in my future. 

If you change to an Aspen that will still have to be aligned to the autopilot with the test box. On many Aspen installations this isn’t done and the result is porpoising.

On a previous airplane I had Aspens, once I had the alignment done the only time my airplane porpoised is when I flew over SeaWorld in San Antonio 

[gabez]

is there a way to avoid or limit the porpoising? or is it just totally random?

[LANCECASPER]

is there a way to avoid or limit the porpoising? or is it just totally random?

The autopilot is doing right now exactly what the attitude indicator is telling it to do. Getting it aligned is the way to avoid or limit porpoising.


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[gabez]

14 minutes ago, LANCECASPER said:

The autopilot is doing right now exactly what the attitude indicator is telling it to do. Getting it aligned is the way to avoid or limit porpoising.


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thank you sir. I emailed a shop in Sacramento to see if they can do it.