UNDERSTANDING THE STABILATOR

[Isham]

Since I am a new owner I want to make sure I understand what is correct or wrong. 

My prior airplane was a Piper Cherokee.  The stabilator on the Piper was close to balanced on pre-flight.  In other words, you could move the stabilator up or down with very little force. 

The CTsw is always down.  When you raise it up at the trim tab it does not hold that position, but moves back to full nose down position.  It just seems like the stick force to raise the stabilator to full nose up position on pre-flight is more than I am used to.  I have not measured the force but I would guess it around 5+ pounds to hold the stabilator up at the trim tab.

Is this normal?

[Runtoeat]

There is an balance box welded to an arm which is welded to the stabilator pivot bracket which balances the stabilator assembly.  When correctly balanced, the stabilator should hold a level position when at rest.  To properly balance the stabilator,  it must be removed with all attaching hardware removed from the airframe but remaining attached to the stabilator.  A fixture to hold the stabilator and allow it to pivot must be made for the bench.  The stabilator is installed in the fixture and lead shot added/removed from the balance box to balance the stabilator.  I describe this due to my experience of carrying out the SB that required reinforcing my stabilator.  I am not an expert so don't take my word as gospel.  You should call Arian at FD USA  to see if there is a published balancing procedure.

[ibjet]

There is a large counterbalance weight on a tube that is connected to the stabilator hinge. As I remember my stabilator is fairly balanced with neutral trim. There is a pretty strong spring that is attached to the stabilator hinge also. When I pre-flight mine, I move the stabilator up and down with 2 hands by moving the stabilator main structure and watch the "trim tab" as it bifurcates up and down (it goes up and down more than the stabilator). So, as I remember, I think mine is more neutrally balanced than you are describing. I had a corroded swivel bearing in mine which drove me crazy for a month until I realized that was the problem. You might look at yours with a flashlight and see if it looks corroded. I think you would need to disconnect the elevator (push/pull) cable to make sure that it swivels freely (it has to swivel for the bell crank feature to work). I wish I could come look at it with you! You probably don't have another CT on your airport to look at/compare to. Mine had a slight binding during travel that was making it hard to flare correctly on landing. Anyway, you might look at the post I did, I shared several pictures. I'll add a link to it here in a few minutes. You will want to get some good lube for all your moving joints back there. I posted a picture of the version I got (it has a needle applicator stem). Just viewed Dicks input, that's great info, confirmed what I remembered, mine is pretty level when trimmed. 

Here is a link to my post, a bit long, the second page has some pictures that will be helpful, one shows the balance weight: 

 

ET  

[Isham]

Based on what you have provided above mine is in need of something.  I will call FDUSA.  Unfortunately, there are not any others around here that I can check for a reference.  Just based on my experience with other airplanes it seemed too hard to lift the stab on pre-flight.  What I can't figure out is why this condition could exist.  I am still going through the logs and hopefully I can find an answer for the root cause.

Glad I asked this question and thank you for your inputs.  ibjet I would appreciate the link.  Runtoeat -- great write up and photos. Thanks.

[ibjet]

I thought I was adding a link, it just shared one picture, grrrrr! I'll have to see how I share that post, my title was "Lubing the stabilator cable" (which is a misnomer, the push/pull cable does not need lube). I will make another attempt . . .

 

[Tom Baker]

What serial number is your CTSW? There are some that were built in 2007 that had a spring added to the stabilator control system that moves the stabilator to the down position.

[Isham]

Mine is 07-03-10.

[Tom Baker]

Does your control stick feel spring loaded to the stick forward position? I'm not sure where the change occurred, but I know a 07-05-** airplane had the springs, and my 06-11-** did not.

[Isham]

Yes, it does feel spring loaded to the nose down position.  Where are the springs located?  Maybe I can look and verify if it has them.

[Tom Baker]

Ask Andy Walker, aka FlyingMonkey his had them, and I think he removed them after he switched to ELSA.

[Runtoeat]

Tom, I didn't realize there was a spring added.  This is why I always recommend making a call to FD USA.  Wonder why a spring was added? Trim would be dialed in for neutral elevator during flight but maybe FD wanted to have a heavy elevator for times when airflow was so low that trim would not maintain this?  Like just before touchdown?   Andy seems to have a good understanding of the dynamics of flight controls and it looks like he may have dealt with this spring.   Any comments Andy?   

[Tom Baker]

38 minutes ago, Runtoeat said:

Tom, I didn't realize there was a spring added.  This is why I always recommend making a call to FD USA.  Wonder why a spring was added? Trim would be dialed in for neutral elevator during flight but maybe FD wanted to have a heavy elevator for times when airflow was so low that trim would not maintain this?  Like just before touchdown?   Andy seems to have a good understanding of the dynamics of flight controls and it looks like he may have dealt with this spring.   Any comments Andy?   

I remember Ed and Andy used to go back and forth on landings and about trimming the aircraft. It wasn't until Ed replaced Woodstock with his new plane that he understood the difference. Flight Design has made many changes since the start of production of the CTSW and CTLS. Most owners think that everyone else's is the same, and sometimes they are not. I have been lucky enough, if you want to call it that, to experience several different variations, and their subtle and sometimes not so subtle differences. The added spring in the control system of the CTSW was one change that I didn't care for, at least from my uneducated point of view.