REFLECTOR: Pitch trim malfunction

[Scott Baker]

John,
In the situations I describe, altitude is easily controlled by applying 
stick pressure.  Changing pitch trim simply helps relieve the need for 
muscle force on the stick.
If you are not able to maintain altitude control through physical control of 
the flight control stick alone, it sounds like something might be 
out-of-whack with the auto pilot or pitch trim mechanism.
If you have the Velocity fiberglass pitch trim spring, be sure to check that 
there is no intereference or binding caused by loose wiring or other items 
behind the panel.  Also check to make sure there is no binding taking place 
in the elevator travel.
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 9:47 PM
Subject: Re: REFLECTOR: Pitch trim malfunction


> Scott,
>
> That's a VERY good question.  It reminds me of a pitch up due to an area 
> of convective rise.  Generally in these cases I can force the nose back 
> down.  Today I pushed hard and the nose didn't come down until 3-4 seconds 
> of down trim.  But maybe that was just a larger than normal convective 
> rise.  Does this describe your experience?  On the other hand, I've only 
> experienced this in recent months and not in the 7 1/2 years of flying 
> previously.
>
> John
>
> --- scottb33333 at gmail.com wrote:
>
> From: "Scott Baker" <scottb33333 at gmail.com>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Subject: Re: REFLECTOR: Pitch trim malfunction
> Date: Thu, 5 May 2011 19:39:29 -0400
>
> 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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