Hirobo 4 x 21 Needle Pin HI2509013 for Helicopter General Parts  [HI2509013]

Linkage needle pin overview

The Hirobo HI2509013 needle pin is an RC replacement component intended for general helicopter assembly use. Identified as a 4 x 21 needle pin within Hirobo helicopter general parts, it offers a simple mechanical fastening option for small linkages and pivot joints.

In operation the pin reduces axial play in rotor linkages and miniature control pivots, which helps preserve control precision. During checks ensure the seating surfaces and adjacent bores are free from ovaling or wear; replace the pin if damage is present.

Typically the pin is fitted as a press-fit into a locating bore or held by the model's existing retainers; it functions as a locating and pivot element rather than a threaded fastener. When setting up, keep axial clearance small to limit slop but avoid forcing the part so it does not bind.