TCW Technologies


Safety-Trim Intelligent Servo Controller



Safety-Trim is an electronic speed control system for standard electric trim servos found on many homebuilt aircraft.   It replaces other speed controllers and relay modules with an electronic solution that resolves issues such as run-away trim and failure to operate conditions. 

Safety-Trim greatly simplifies trim switch wiring, especially when installing pilot and co-pilot switches.    Safety-Trim is available with 2 Speed operation, allowing automatic high and low speed trim actuation.


Safety-Trim Servo Booster is now avialable.  Controls servos up to 10 amps from Garmin G3x autopilot and Dynon autopilot.    SEE ORDERING TAB to purchase

Learn how Safety-Trim works   (click here)               

Online ordering (click here)

Download the  Installation Manuals       

Read what Tim Olson had to say about his installation in his RV-10   N104CD

   Safety-Trim  Features & Benefits:


  •  Electronic servo controller with speed control run-away protection

  •  Time limited operation prevents trim servo run-away conditions

  •  Servo travel limited to 3 seconds per trim switch actuation

  •  Reverse function switch allows pilot to recover from a stuck or failed trim switch

  •  Eliminates many other components, no extra relay decks or speed controllers needed

  •  Very simple wiring, no extra parts needed for pilot and co-pilot trim switches

  •  Designed for standard electric trim servos, such as the Ray Allen T2 & T3 series

  •  Model available for servos up to 10 amps. 

  •  Short circuit proof, reverse polarity protected

  •  1 axis, 2 axis models available

  •  User adjustable, 1 speed and 2 speed models available

  •  For Experimental aircraft only    NOT TSO'd

  •  Made in USA -- US patent 7,719,200

Installation Manuals

We are proud of our products and our installation manuals,  we would like you to take a close look.  Our actual product installation manuals are available here for you to download.   We want you to understand how our products work and how to install them properly.   We are trying to raise the bar on the quality of instruction manuals provided for homebuilt aircraft accessories.

Download the actual product installation manuals :

pdf Installation Instructions for Safety Trim Servo Booster:  ST-1-12v-10a-BSTR, ST-1-24v-10a-BSTR

 Installation Instructions for single axis controllers: models ST-1-12v & ST-1-12v-2sp   (right click to save a copy)

  Installation Instructions for dual axis controllers: models ST-2-12v & ST-2-12v-2sp  (right click to save a copy)

   Installation Instructions for HD model : model ST-1-12v-2sp-HD  (right click to save a copy)

   Wiring Harness Detailed Drawing


   Pre-made wiring harness                           Airspeed Switch


Visit our Application Notes page important details on typical installations




ST-1-12v                single axis intelligent servo controller                                                $185

ST-1-12v-2sp        single axis intelligent servo controller w/ 2 speed presets            $245

ST-1-12v-2sp-HD single axis servo controller w/2 speed presets, Heavy Duty         $245


ST-2-12v                 dual axis intelligent servo controller                                                 $285

ST-2-12v-2sp        dual axis intelligent servo controller w/ 2 speed presets               $345


ASW-1                     air speed switch for triggering 2 speed function                               $49

Wiring harness available:  We offer an aircraft grade wiring harness for all models.   The wiring harness is 8ft long, color coded and utilizes mil-spec wire and connector terminations.   Additionally, it includes the recommended  ON/OFF/Reverse switch. 

On-line ordering:      

Solution Graphics

Single axis models:

 Model  ST-1-12v           Single axis servo controller                                  $185       

 Model  ST-1-12v-2sp     Single axis servo controller with 2 speed presets      $245      

 Model  ST-1-harn          Wiring harness for all single axis servo controllers    $65       

Model ST-1-12v-2sp-HD  Single axis servo controller with 2 speed presets- Heavy Duty $245
Model ST-1-harn-HD         Wiring harness for Heavy Duty Safety trim                        $65 

Dual axis models:

 Model ST-2-12v           dual axis servo controller                                    $285           
 Model ST-2-12v-2sp     dual axis servo controller with 2 speed presets      $345           
 Model ST-2-harn            wiring harness for all dual axis servo controllers   $85           

Model ASW-1       Airspeed switch 55-140 knots    $49         

A paypal account is not required to order, just a credit card.



Ordering  by mail or by phone:

TCW Technologies, LLC.

2955 Main Road East

Emmaus, PA 18049


OR CALL:  610-928-3420

Your phone call or email is always welcome!


Additional Information:





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Copyright © 2007-2017 TCW Technologies, LLC.
Last modified 1-18-2017

US Patent 7,719,220 on Safety-Trim and Flap Controller products

US Patent 7,868,478 on IPS product

US Patent 8,189,305 on IBBS products