Upgrade Case for S3153-size Servos - Futaba FUAS4139  [FUAS4139]

Installation and bench-use guide

The Futaba FUAS4139 case is an aftermarket-style housing made to hold S3153-size servos during installation, testing, and routine swaps. Supplied without retail packing, it is supplied as a replacement or service accessory to secure the servo body in model applications.

Designed around the S3153 external dimensions, the case accommodates servos that share the same outer measurements. It provides a stable mounting envelope to keep the servo aligned with the model's attachment points and to reduce movement while adjusting linkages or tuning the setup. Servos and electronics are not part of the set.

When fitting the servo, ensure the output spline and shaft are unobstructed, check clearance for the horn and servo linkages, and fit using your model's existing screws and spacers. The case speeds repeatable positioning for rapid swaps during bench testing or field adjustments.