Frank Mooney

Help! Want to keep Manual electric trim and remove autopilot

Recommended Posts

In my quest to upgrade my panel it was decided to remove the old autopilot and install 2 G5's along with all the other avionic upgrades. I was informed that in removing my old autopilot that the electric manual trim will not work and was asked if anyone on the forum has had this challenge also and over come? Any suggestions or answers to this are greatly appreciated as I cant see myself enjoying manual trimming this bird!! 

Share this post


Link to post
Share on other sites

*Members that donate $10 or more do not see advertisements*

Frank,

Which old AP do you have?

It would seem that it is still useful to you. So why remove it until ready to replace with something newer?

Best regards,

-a-

  • Like 1

Share this post


Link to post
Share on other sites

Trim changes are relatively minor throughout a normal flight. Don’t think you will have an issue. 

Share this post


Link to post
Share on other sites
27 minutes ago, carusoam said:

Frank,

Which old AP do you have?

It would seem that it is still useful to you. So why remove it until ready to replace with something newer?

Best regards,

-a-

Old  AP was KFC200 

And the autopilot was inop plan on adding a trutrak once it is certified when ever that is. My auto manual trim worked great and the avionics guy thought It might work without the old AP removed but that is proving difficult. 

  • Like 1

Share this post


Link to post
Share on other sites

If your K model was offered with electric trim but no autopilot that’s the configuration you need.  

You may not remove some parts of your autopilot system and retain just the electric trim portion.  

The system block diagram hints at why:

3EF587F7-3517-40B5-84C1-48C347147712.jpeg.8f2dbf76d92924e56a217e734d1305fd.jpeg

The pitch trim servo takes its input from the computer, not directly from the trim switches on the yoke.  

The yoke’s cutout button function needs to be retained too.  It is important to be able to cut all power to the servo if it runs uncontrollably.  (Just ask Lion Air).  

  • Like 2

Share this post


Link to post
Share on other sites

Call Bendix King and talk to tech support.  We are also pulling our KFC200 and wanted to keep the electric trim.  They said I couldn't do that but they sent me a PDF copy of the installation manual for the F and J (I have a J).  Low and behold, one of the options listed in the installation manual was the 'trim only' option.  That is, electric trim without an autopilot.  After I found that in the manual I called them back.  They were surprised but agreed I could do that so they found and sent me a copy of the STC for the trim only system.  They may have something similar for your K.

  • Like 2

Share this post


Link to post
Share on other sites
9 hours ago, Bob - S50 said:

Call Bendix King and talk to tech support.  We are also pulling our KFC200 and wanted to keep the electric trim.  They said I couldn't do that but they sent me a PDF copy of the installation manual for the F and J (I have a J).  Low and behold, one of the options listed in the installation manual was the 'trim only' option.  That is, electric trim without an autopilot.  After I found that in the manual I called them back.  They were surprised but agreed I could do that so they found and sent me a copy of the STC for the trim only system.  They may have something similar for your K. 

Wow Great news this is an excellent start on the road to "trim Recovery" Thanks!! 

Share this post


Link to post
Share on other sites

Over the last couple of years the AP computer for the KAP 150 in my M20J had to come out for repairs. The computer was out for several months while AP Central found the flaky problem. I got tired of manual trim so I spent some time in the maintenance manual and noticed the electric trim switch went into the computer and the computer turned that signal around to drive the servo. I tried a jumper across the connector pins and the manual trim started working without the computer. The following are my notes on how to enable the electric trim with the computer removed.

The trim engage switch is read by the AP computer and the trim clutch is engaged by the AP computer. A jumper allows the trim servo clutch to be engaged by the trim switch. 

First picture shows the parts and tools used.  Use the black plug to plug the static line for the AP computer. Install jumper between pins P1911 H and F. Top connector, top row jumper pins 6 and 7 from the left. Jumper pins used are intermediate sized MIL-STD with heat shrink to keep pins from shorting against frame. Second picture shows the jumper installed. 

I had the jumper installed for several months over a couple of years without any problems. I can't speak to the legal aspects, STCs required but it does work. 

Jim

20180825_093809.jpg

20180825_093227.jpg

  • Like 4

Share this post


Link to post
Share on other sites

I have a KFC 200 in my 81J model.  The computer was taken out for repairs recently. I was surprised that the electric trim still worked. Don't because anything special was done.

 

 

Share this post


Link to post
Share on other sites

I haven't taken the time to do an in depth look at the wiring diagram in the installation manual, but from a cursory look it appears that the trim switch connects directly to the pitch trim.  The autopilot also has a connection to the trim servo.  There are also some other connections.  I suspect that either the autopilot or switch can run the trim servo but the other wiring is there to alert the autopilot if the servo is run by the switch so the autopilot can disengage when that happens.

Share this post


Link to post
Share on other sites
On ‎12‎/‎4‎/‎2018 at 11:56 PM, Bob - S50 said:

Call Bendix King and talk to tech support.  We are also pulling our KFC200 and wanted to keep the electric trim.  They said I couldn't do that but they sent me a PDF copy of the installation manual for the F and J (I have a J).  Low and behold, one of the options listed in the installation manual was the 'trim only' option.  That is, electric trim without an autopilot.  After I found that in the manual I called them back.  They were surprised but agreed I could do that so they found and sent me a copy of the STC for the trim only system.  They may have something similar for your K.

Called and they do NOT have STC for the "K" Model... Guess I have to wait until the Garmin GFC500 gets certified for Mooney to couple to my G-5s 

Share this post


Link to post
Share on other sites
20 hours ago, Frank Mooney said:

Called and they do NOT have STC for the "K" Model... Guess I have to wait until the Garmin GFC500 gets certified for Mooney to couple to my G-5s 

Did you ask if they have  a copy of the installation manual for the K?  That's where I found it.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now