# Trim tab and antiservo tab

> How does a trim tab work?

- Category: Aircraft design › Control surfaces
- Kind: Standard part
- Basis: Design rules and figures from the cited sources; example geometry by Xem Studio
- Page: https://xemstudio.com/objects/trim-tab/ · JSON: https://xemstudio.com/api/geometry?object=trim-tab · Plain text: https://xemstudio.com/objects/trim-tab/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** True size, with no printing tolerance added.

## Notes

- A trim tab is a small surface on a control surface's trailing edge that moves opposite to the surface, holding it deflected so the pilot needn't; full nose-down trim moves the elevator tab full up (FAA PHAK ch.6).
- On a stabilator an antiservo tab moves the same way as the surface to add feel and prevent over-control (FAA).

## Sizes

| parameter | value or range | source |
|---|---|---|
| Trim tab motion | opposite to the surface | FAA PHAK ch.6 |
| Antiservo tab motion | same direction as stabilator | FAA PHAK ch.6 |

## Where the files are

- FAA: [Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25), Ch. 6 Flight Controls](https://www.faa.gov/sites/faa.gov/files/08_phak_ch6.pdf) — web — Publisher's page; dimensions are facts

## Questions

**Which way does a trim tab move?**

Opposite to its control surface (FAA PHAK ch.6).

## Fits with

- [Aileron](https://xemstudio.com/objects/aileron/)
- [Frise aileron](https://xemstudio.com/objects/frise-aileron/)
- [Differential ailerons](https://xemstudio.com/objects/differential-ailerons/)
- [Elevon](https://xemstudio.com/objects/elevon/)
- [Flaperon](https://xemstudio.com/objects/flaperon/)
- [Spoiler](https://xemstudio.com/objects/spoiler/)