The RAC T3-12A is an electric linear trim servo actuator used in aircraft trim systems to control aerodynamic trim surfaces such as elevator, rudder, or aileron trim. It is part of the Ray Allen T-series servo family and uses a jackscrew-driven linear motion mechanism to precisely position control surfaces.

The unit operates on 12–14V DC power and responds directly to polarity reversal: changing polarity determines direction of travel (extend or retract). It includes internal mechanical end-stops and will automatically stop at full travel limits without requiring external electronics or limit switches.

When power is removed, the jackscrew mechanism locks in position, maintaining trim setting without back-driving. The servo is designed for use in experimental and light aircraft trim systems, typically installed with a control switch, indicator, and pushrod linkage.

Key features include:

RAC part number: T3-12A
Electric linear trim servo (jackscrew type)
Operating voltage: 12–14V DC
Linear travel: approx. 1.2 in (31 mm)
Self-locking mechanism when power is off
Direction controlled by polarity reversal
Built-in end-of-travel automatic stop
Designed for aircraft trim surface control
Used in elevator, rudder, or aileron trim systems
Suitable for experimental and light aircraft applications
High-force linear actuator for aerodynamic trimming
Includes mounting provisions for pushrod linkage