Posted for "Gigliotti, James M Mr DCD\(CAMBER\)" <james.gigliotti@us.army.mil>:

 Wolfgang Meyn wrote:
 
"""
 So today I would like to ask you to chime in and maybe the two groups
 together can shed more light into the darkness and get TruTrak to the
 point that they fix these ongoing problems.
 
 What I am specifically interested in is:
 
 1.                   What TT unit do you use?
 2.                   What problems did you encounter?
 3.                   Under what conditions do the problems occur?
 4.                   What fix did TT offer?
 5.                   Did the fix work?
"""
 
  Hello Wolfgang
 
  I have been using the TT Altrak VS Altitude Hold and Pictoral
 Pilot for about 6 months now.  I had heard scuttlebutt that aircraft
 like the Lancair can have difficulties with porpoising with the altitude
 hold engaged.  Sure enough, I have that problem.
  The Altrak has three settings to control the activity level.
 These settings have a pronounced effect on the porpoising, but the best
 I can get still leaves me with occasional minor porpoising that occurs
 maybe two or three times during a typical flight in calm air.  I can
 control the problem somewhat by adding some up-trim to the elevator, but
 this doesn't always work.  The porpoising is not severe, but I'm certain
 if I were in clouds, it would be sever enough for me to want to
 disengage the altitude hold if I were not able to correct the problem
 after a minute or two.
  I haven't contacted TT directly yet to discuss this problem with
 them.  I'm hopeful that, when I do, they will have some good tips for
 me.
 
  I wonder if anyone else has had this difficulty, and what they
 did to solve it?
 
 Respectfully,
 
 Jim.