From: "Marvin Kaye" <marv@lancaironline.net>
Subject: Re: [LML] Re: trim vs. a/p
To: lml
Date: Thu, 16 Nov 2006 12:44:42 -0500
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In-Reply-To: <455C60B9.80708@club-internet.fr>
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 <455C60B9.80708@club-internet.fr>
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Posted for Alain NOIREAUX <alainoireaux@club-internet.fr>:

  colyncase on earthlink a écrit :
  
> my stec 55x (on my cessna) has auto-trim, which means the auto-pilot 
> senses the torque required to
> maintain the desired flight condition and adjusts the trim to keep 
> that torque within some pre-specified
> limit.
>  
> However, there is a pilot controlled trim switch.  If the pilot makes 
> a trim change directly, the a/p
> disengages.   The reason for this is that if it didn't, you could dial 
> in lots of trim but you wouldn't
> feel it because the a/p would be counteracting it, until it couldn't 
> any more at which time it will
> disengage and hand you the airplane way out of trim, resulting in an 
> "excursion"

  It is the only safe way to work with an A/P . Either your A/P has an 
autotrim
fonction and trims the pitch control itself,when needed,or you  have it
disconnected automatically as soon as you touch your  electric trim command .
If you don't have one of these fonctions ,or have a manual trim,YOU MUST
disconnect yourself the A/P to trim the pitch control, to avoid your plane
going brutally nose Up or Down when the A/P cannot anymore control  the pitch
.
  
  Alain Noireaux