# STC SA09321AC-D

- Type: Supplemental type certificate
- Status: Current, Issued
- Holder: S-TEC Corporation, United States
- Description: Installation of S-TEC System 30 alt altitude hold system Model ST-721
- Applied: December 31, 1997
- Status date: January 3, 1998
- Product: Aircraft, Single-Engine
- Certification basis: Part 21, Part 31
- Data sheets: [TCDS 5A6](https://openairdocs.org/tcds/5A6)
- Certificate PDF: https://openairdocs.org/files/sha256/d1/8c/d18c2a28e0bf75c4dc15ff6683c52388b84c8e17520fdd3d91b6c4739747cd79
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/E86E620903E5C77B85256CC1007F3A8A.0001
- DRS record last changed: December 6, 2025
- Page: https://openairdocs.org/stc/SA09321AC-D

## ADs that name it (0)

None.

## Approved models (11)

- Cessna Aircraft Company 180 ([TCDS 5A6](https://openairdocs.org/tcds/5A6))
- Cessna Aircraft Company 180A ([TCDS 5A6](https://openairdocs.org/tcds/5A6))
- Cessna Aircraft Company 180B ([TCDS 5A6](https://openairdocs.org/tcds/5A6))
- Cessna Aircraft Company 180C ([TCDS 5A6](https://openairdocs.org/tcds/5A6))
- Cessna Aircraft Company 180D ([TCDS 5A6](https://openairdocs.org/tcds/5A6))
- Cessna Aircraft Company 180E ([TCDS 5A6](https://openairdocs.org/tcds/5A6))
- Cessna Aircraft Company 180F ([TCDS 5A6](https://openairdocs.org/tcds/5A6))
- Cessna Aircraft Company 180G ([TCDS 5A6](https://openairdocs.org/tcds/5A6))
- Cessna Aircraft Company 180H ([TCDS 5A6](https://openairdocs.org/tcds/5A6))
- Cessna Aircraft Company 180J ([TCDS 5A6](https://openairdocs.org/tcds/5A6))
- Cessna Aircraft Company 180K ([TCDS 5A6](https://openairdocs.org/tcds/5A6))

## 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: SA09321 AC-D This certificate issued to: S-TEC Corporation One S-TEC Way Mineral Wells Municipal Airport Mineral Wells, TX 76067-9236 I art 3 of the Civil I is Regulations.

Original Product I ype Certifiate A umber: SA6 Make: Cessna Model: 180, 180A, 180B, 180C, 180D, 180E, 180F, 180G, 180H, 180J, and 180K Description of Type Design Change:

Installation of S-TEC System 30 ALT Altitude Hold System, Model ST-721, according to Bulletin No 821, dated 12-30-97 and Master Drawing List No. 921058, dated 12-30-97 or later PAA Approved revisions of the above data (14 Volt System).

Also eligible on The Above Models When Modified Per STC SA1705WE (Internal Tip Tanks) and/or STC SA 1435WE (Robertson STOL) (Landplane, Floatplane or Amphibian).

(Sce Continuation Sheet, Page 2, a part of this STC.)

suspended, revched or a termination date is otherase established by the Administrator of the Federal viation Administration.

Date of Application: 12-31-97 Date Reissued:

Date of Issuance: . 1-03-98 Date Amended:

By Direction of the Administrator FEDERAL AVIATION Wirin Shone * TOMINSTRATO William J. Thomas DAS Staff Coordinator, DAS 5 SW (Title)

This certificate may be transferred In

United States of America Department of Transportation Federal Aviation Administration Supplemental Type Certificate (Continuation Sheet) Number: SA09321AC-D Limitations and Conditions: (con't.)

N FAA/DAS Approved Supplemental Flight Manual, P/N 891624, dated 1-03-98 is required for Cessna Models 180, 180A, 180B, 180C, 180D, 180E, and 180F (Landplane, Floatplane or Amphibian) and The Above Models When Modified per STC SA 1705WE (Internal Tip Tanks) and/or STC SA1435WE (Robertson STOL) or later FAA Approved revisions of the above supplement.

3. FAA/DAS Approved Supplemental Flight Manual, P/N 891625, dated 1-03-98 is required for Cessna Models 180G, 180H, 180J; and 180K, S/N 18053000 and Below (Landplane, Floatplane or Amphibian) and The Above Models When Modified Per STC SA1705WE (Internal Tip Tanks) and/or STC SA 1435WE (Robertson STOL) or later FAA Approved revisions of the above supplement.

4. FAA/DAS Approved Pilot's Operating Handbook and/or Airplane Flight Manual Supplement, P/N 891626, dated 1-03-98 is required for Cessna Model 180K, S/N 18053001 and Up (Landplane, Floatplane or Amphibian) and The Above Model When Modified Per STC SA1705WE (Internal Tip Tanks) and/or STC SA1435WE (Robertson STOL) or later FAA Approved revisions of the above supplement.

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

47.

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 code) Extent of Authority (if licensing agreement):

Signature of grantor (In ink):

## Every issue (1)

- January 3, 1998: Issued, Current. [certificate](https://openairdocs.org/files/sha256/d1/8c/d18c2a28e0bf75c4dc15ff6683c52388b84c8e17520fdd3d91b6c4739747cd79)

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