# STC SA09224AC-D - Type: Supplemental type certificate - Status: Current, Amended - Holder: S-TEC Corporation, United States - Description: Installation of S-TEC System 20/30 Single and Two Axis Automatic Flight Guidance Systems Model ST-685-20/30. - Status date: September 10, 1999 - Product: Aircraft, Single-Engine - Certification basis: Part 21 - Data sheets: [TCDS 3A12](https://openairdocs.org/tcds/3A12) - Certificate PDF: https://openairdocs.org/files/sha256/e3/71/e371c986d74e29804daa244e255d3ccf7d573eab030150289d1e2d814ed4d1c4 - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/DBB7BFC824E36C9A85256CC1007F3A28.0001 - DRS record last changed: December 6, 2025 - Page: https://openairdocs.org/stc/SA09224AC-D ## ADs that name it (0) None. ## Approved models (12) - The Cessna Aircraft Company 172 ([TCDS 3A12](https://openairdocs.org/tcds/3A12)) - The Cessna Aircraft Company 172A ([TCDS 3A12](https://openairdocs.org/tcds/3A12)) - The Cessna Aircraft Company 172B ([TCDS 3A12](https://openairdocs.org/tcds/3A12)) - The Cessna Aircraft Company 172C ([TCDS 3A12](https://openairdocs.org/tcds/3A12)) - The Cessna Aircraft Company 172D ([TCDS 3A12](https://openairdocs.org/tcds/3A12)) - The Cessna Aircraft Company 172E ([TCDS 3A12](https://openairdocs.org/tcds/3A12)) - The Cessna Aircraft Company 172F (USAF T-41A) ([TCDS 3A12](https://openairdocs.org/tcds/3A12)) - The Cessna Aircraft Company 172G ([TCDS 3A12](https://openairdocs.org/tcds/3A12)) - The Cessna Aircraft Company 172H (USAF T-41A) ([TCDS 3A12](https://openairdocs.org/tcds/3A12)) - The Cessna Aircraft Company 172I ([TCDS 3A12](https://openairdocs.org/tcds/3A12)) - The Cessna Aircraft Company 172K ([TCDS 3A12](https://openairdocs.org/tcds/3A12)) - The Cessna Aircraft Company 172L ([TCDS 3A12](https://openairdocs.org/tcds/3A12)) ## What the certificate says This is OCR from the scanned FAA certificate. OCR can misread letters and numbers. United States of America Department of Transportation Federal Aviation Administration Supplemental Type Certificate Number: SA09224AC-D This certificate issued to: S-TEC Corporation One S-TEC Way Mineral Wells Municipal Airport Mineral Wells, TX 76067-9236 Certifies that the change in the type design for the fellowing product with the linitations and conditions therefer as specified hereen meets the aircorthiness requiements of Part 3 of the Finit Lis hequlations. Original Product I ype Certifente A unter: 3A12 Make s Cessna Model: 172, 172A, 172B, 172C, 172D, 172E, 172F, 172G, 172H, 1721, 172K, and 172L Description of Type Design Change: Installation of S-TEC System 20/30 Single and Two Axis Automatic Flight Guidance Systems, Model ST-685-20/30, according to Bulletin No. 785, Revision 4, dated 1-15-99 and Master Drawing List No. 92997, Revision D, dated 1-15-99 or later FAA Approved revisions of the above data (14 Volt System). Also eligible on the above models when modified per STC SA420CE (180 H.P. engine conversion). (See Continuation Sheet, Page 2, a part of this STC.) 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. Date of Application: 5-21-97 Date Reissued: I ate of ismure: 5-23-97 Date Amended: 1-20-99, Revision 1 By Direction of the Administrator FEDERAL AVIATION (Signature) TOMINISTRATO Michael Keirnan DAS Staff Coordinator, DAS 5 SW (Title) United States of America Department of Transportation Federal Aviation Administration Supplemental Type Certificate Number: SA09224AC-D, Revision 1 Limitations and Conditions: (con't.) Also eligible on models 172D, 172E, 172F, 172G, 1752H, 1721, 172K, and 172L when modified per STC SA4428SW (180 H.P. engine conversion). 3. FAA/DAS Approved Supplemental Flight Manual, P/N 891390, dated 5-23-97 is required for Cessna Models 172, 172A, 172B, and 172C And The Above Models When Modified Per STC SA420CE (Lycoming Engine 0-360-A1D, 180 H.P.) for S-TEC System 20 or later FAA Approved revisions of the above supplement. 4. FAA/DAS Approved Supplemental Flight Manual, P/N 891391, dated 5-23-97 is required for Cessna Models 172D, 172E, 172F, 172G, 172H, 1721, 172K, and 172L And The Above Models When Modified Per STC SA420CE (Lycoming Engine 0-360-AID, 180 H.P.) for S-TEC System 20 or later FAA Approved revisions of the above supplement. 5. FAA/DAS Approved Supplemental Flight Manual, P/N 891396, dated 5-23-97 is required for Cessna Models 172, 172A, 172B, and 172C And The Above Models When Modified Per STC SA420CE (Lycoming Engine 0-360-A1D, 180 H.P.) for S-TEC System 30 or later FAA Approved revisions of the above supplement. 6. FAA/DAS Approved Supplemental Flight Manual, P/N 891397, dated 5-23-97 is required for Cessna Models 172D, 172E, 172F, 172G, 172H, 1721, 172K, and 172L And The Above Models When Modified Per STC SA420CE (Lycoming Engine 0-360-A1D, 180 H.P.) for S-TEC System 30 or later FAA Approved revisions of the above supplement. 7. PAA/DAS Approved Supplemental Flight Manual, P/N 891390, Revision 1, dated 1-20-99 is required for Cessna models 172, 172A, 172B, and 172C and the above models when modified per STC SA420CE (180 H.P. engine conversion) for S-TEC System 20 or later FAA Approved revisions of the above supplement. FAA/DAS Approved Supplemental Flight Manual, P/N 891391, Revision 1, dated 1-20-99 is required for Cessna models 172D, 172E, 172F, 172G, 172H, 1721, 172K, and 172L and the above models when modified per STC SA420CE or STC SA4428SW (180 H.P. engine conversions) for S-TEC System 20 or later FAA Approved revisions of the above supplement. 9. FAA/DAS Approved Supplemental Flight Manual, P/N 891396, Revision 1, dated 1-20-99 is required for Cessna models 172, 172A, 172B, and 172C and the above models when modified per STC SA420CE (180 H.P. engine conversion) for S-TEC System 30 or later FAA Approved revisions of the above supplement. 10. FAA/DAS Approved Supplemental Flight Manual, P/N 891397, Revision 1, dated 1-20-99 is required for Cessna models 172D, 172E, 172F, 172G, 172H, 1721, 172K, and 172L and the above models when modified per STC SA420CE or STC SA4428SW (180 H.P. engine conversions) for S-TEC System 30 or later FAA Approved revisions of the above supplement. 11. Compatibility of this modification with other previously approved modifications must be determined by the installer. TRANSFER ENDORSEMENT Transfer the ownership of Supplemental Type Certificate Number to (Name of transferee) (Address of transferee) (Number and street) (City, State, and ZIP code) from (Name of grantor) | Print or type) (Address of grantor) (Number & street! (City, State, and ZIP codel Extent of Authority (if licensing agreement): Signature of grantor (In ink): ## Every issue (1) - January 20, 1999: Amended, Historical. [certificate](https://openairdocs.org/files/sha256/e3/71/e371c986d74e29804daa244e255d3ccf7d573eab030150289d1e2d814ed4d1c4) --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.