Futaba S3115/S3116 Compatible Replacement Case FUAS4138  [FUAS4138]

S3115/S3116 compatible shell

This Futaba FUAS4138 servo case set is supplied as a direct replacement housing for Futaba S3115 and S3116 servos without retail packaging. The focus here is on correct fit and serviceability for hobby RC servos rather than performance enhancement claims.

Compatibility note: this case is designed for the S3115 and S3116 models named; other Futaba servos may differ in mounting points or internal layout. The case is useful to swap out damaged housings, re-secure the gear train and PCB, and restore correct internal geometry during servicing.

Practical assembly advice: remove the servo horn and outer shell, record the orientation of gears and electronics, move components into the replacement case checking for proper clearance and screw torque, then reassemble and confirm full travel and centering with your transmitter. Keep any metal shims or bearings in their original positions to preserve gear alignment.

Role in tuning and service: this part supports accurate reassembly after repairs and helps preserve mechanical alignment that affects smooth operation and consistent feedback. It should be treated as a maintenance item rather than an upgrade to increase performance.