# STC SA821SO

- Type: Supplemental type certificate
- Status: Current, Issued
- Holder: Bendix Corporation Avionics Div, United States
- Description: Installation of Bendix M-4D automatic flight control system including optional flight director system and integration into existing Swearingen pitch trim system.
- Status date: January 29, 1975
- Product: Aircraft, Small Multi-Engine
- Certification basis: Part 21
- Data sheets: [TCDS A5SW](https://openairdocs.org/tcds/A5SW), [TCDS A8SW](https://openairdocs.org/tcds/A8SW)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/16DBE69FFAEA1AED85256CC20058E696.0001
- DRS record last changed: December 6, 2025
- Page: https://openairdocs.org/stc/SA821SO

## ADs that name it (0)

None.

## Approved models (2)

- Fairchild Aircraft Corporation SA226-AT ([TCDS A5SW](https://openairdocs.org/tcds/A5SW))
- Fairchild Aircraft Corporation SA226-TC ([TCDS A8SW](https://openairdocs.org/tcds/A8SW))

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