# STC SA09120AC-D

- Type: Supplemental type certificate
- Status: Current, Amended
- Holder: S-TEC Corporation, United States
- Description: Installation of S-TEC System 55/55X Two Axis automatic flight guidance system, Model ST-603
- Applied: September 21, 1995
- Status date: August 3, 2021
- Product: Aircraft, Small Airplane
- Certification basis: Part 21
- Data sheets: [TCDS A6CE](https://openairdocs.org/tcds/A6CE)
- Certificate PDF: https://openairdocs.org/files/sha256/b9/f4/b9f4d3d95f1472b7badcd270993926b067cbd5801246ba1ba23e884c603de73d
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/9959A3F8A04CC26D86258728006FE54F.0001
- DRS record last changed: December 6, 2025
- Page: https://openairdocs.org/stc/SA09120AC-D

## ADs that name it (0)

None.

## Approved models (19)

- Textron Aviation Inc. 337 ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. 337A ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. 337B ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. 337C ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. 337D ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. 337E ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. 337F ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. 337G ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. 337H ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. M337B ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. P337H ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. T337B ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. T337C ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. T337D ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. T337E ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. T337F ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. T337G ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. T337H ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))
- Textron Aviation Inc. T337H-SP ([TCDS A6CE](https://openairdocs.org/tcds/A6CE))

## What the certificate says

Read from the PDF's text layer, without the form's printed wording; the layout is lost and the order can differ. The PDF is the record.

SA09120AC-D S-TEC Corporation One S-TEC Way Mineral Wells Municipal Airport Mineral Wells, TX 76067-9236 23 Code of Federal Regulations A6CE Textron Aviation Inc.

337, 337A, 337B, M337B, T337B, 337C, T337C, 337D, T337D, 337E, T337E, 337F, T337F, 337G, T337G, 337H, P337H, T337H, and T337H-SP

1. Installation of an S-TEC System 55/55X Two Axis Automatic Flight Guidance System, in accordance with Master Drawing List No. 92806, Revision E, dated 7-29-21 or later FAA approved revision.

2. Airplane Flight Manual Supplement, 891198 , Rev. 2, dated 8-03-21 or later FAA approved revision is required.

3. Airplane Flight Manual Supplement, 891199, Rev. 2, dated 8-03-21 or later FAA approved revision is required. (See continuation sheet 3)

1. Also eligible on the above models when modified per STC SA937CE (Horton STOL Craft Conversion).

2. Also eligible on the above models when modified per STC SA1627WE (Robertson STOL Conversion) (See continuation sheet 3) September 21, 1995 September 29, 1995 April 19, 2001, August 03, 2021 3

SA09120AC-D 3

SA09120AC-D Description of Type Design Changes:

4. Instructions for Continued Airworthiness, ST-603-ICA-0001, Revision -, dated 7-12-21, or later FAA approved revision is required.

3. This STC is applicable to all serial numbers for Textron Aviation Inc. models 337, 337A, 337B, M337B, T337B, 337C, T337C, 337D, T337D, 337E, T337E, 337F, T337F, 337G, T337G, 337H, P337H, T337H, and T337H-SP.

4. Compatibility of this modification with other previously approved modifications must be determined by the installer.

5. If the holder agrees to permit another person to use this certificate to alter the product, the holder shall give the other person written evidence of that permission.

END

August 03, 2021 3 3

## Every issue (2)

- August 3, 2021: Amended, Current. [certificate](https://openairdocs.org/files/sha256/b9/f4/b9f4d3d95f1472b7badcd270993926b067cbd5801246ba1ba23e884c603de73d)
- April 19, 2001: Amended, Historical. [certificate](https://openairdocs.org/files/sha256/7f/d3/7fd313392eb6f5b6103c1e326626c134568aabf21bd164804adf41a709770746)

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