REFLECTOR: Pitch trim malfunction

[Scott Baker]

John,
When flying Velocity aircraft I have often experienced a pitch up upon 
entering clouds or precip - and of course when entering an area of 
convective rise activity - to the point where pitch 'down' trim is needed. 
Soon thereafter the flight situation will call for pitch Up trim.  Might 
these describe what is happening to you?  Or do you feel the pitch trim is 
actually running away?
Scott B.


----- Original Message ----- 
From: <aminetech at bluefrog.com>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Thursday, May 05, 2011 6:39 PM
Subject: REFLECTOR: Pitch trim malfunction


> Several times a few months ago and another time today, it seemed like my 
> pitch trim trimmed up uncommanded.  I had to apply forward stick pressure. 
> After a few seconds of pressing the down trim button, the stick pressure 
> went away.  I have the MAC G7 stick.  I have solid state relays.  In the 
> past the up trim relay failed and I had to land with the trim stuck in the 
> full down position.
>
> My questions are:
>
> 1) What can the cause be?  A stuck button on the stick?  A malfunctioning 
> relay?  The trim motor?
>
> 2)  Would one of the above failure modes result in shorting out the trim 
> circuit when I press the trim down button?  If so, then that failure mode 
> can be eliminated since a short does not happen.
>
> 3)  Is anyone using this stick without relays?  Maybe I could eliminate 
> the relays and make it simplier.
>
> Thanks,
>
> John
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