# STC SA1921SW

- Type: Supplemental type certificate
- Status: Current, Amended
- Holder: Wall Colmonoy Corp, United States
- Description: Installation of Exhaust System Muffler Assembly
- Applied: September 27, 1974
- Status date: June 5, 2019
- Product: Aircraft, Small Airplane
- Certification basis: Part 23
- Data sheets: [TCDS 3A12](https://openairdocs.org/tcds/3A12), [TCDS A13CE](https://openairdocs.org/tcds/A13CE)
- Certificate PDF: https://openairdocs.org/files/sha256/99/54/99543242150b1d9cc4a50e52419862dadd915f72af6fc3d2e6474b5277b9605a
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/DDFD8C4C2FE148E78625858B003F56F1.0001
- DRS record last changed: December 5, 2025
- Page: https://openairdocs.org/stc/SA1921SW

## ADs that name it (0)

None.

## Approved models (21)

- Textron Aviation Inc. 172 ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172A ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172B ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172C ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172D ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172E ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172F (USAF T-41A) ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172G ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172H (USAF T-41A) ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172I ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172K ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172L ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172M ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172N ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172P ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172Q ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172R ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 172S ([TCDS 3A12](https://openairdocs.org/tcds/3A12))
- Textron Aviation Inc. 177 ([TCDS A13CE](https://openairdocs.org/tcds/A13CE))
- Textron Aviation Inc. 177A ([TCDS A13CE](https://openairdocs.org/tcds/A13CE))
- Textron Aviation Inc. 177B ([TCDS A13CE](https://openairdocs.org/tcds/A13CE))

## 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.

United States of America Department of Transportation Federal Aviation Administration Supplemental Type Certificate � 
         
             
          
  
        
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            � � ˆ & !  ˆ  ° ˜ ! "  ˆ  "  ' ˆ � � ˘ )    * " & + ,  ° ' $     This certificate issued to:

of the

By Direction of the Administrator Signature Title G G 2 2 9 9 > > 5 5 @ @ M K H = H 7 = 2 3 / 1 8 8 2 > 9 / D 5 1 D G G 2 2 9 9 > > L K > B / H > H 1 7 6 > > 6 6 D D SA1921SW Wall Colmonoy Corporation 4700 SE 59th Street Oklahoma City, Oklahoma 73135 Part 23 Code of Federal Regulations.

Installation of Exhaust System Muffler Assembly Nos. SO-00127A, SO-00127B-2 according to Drawing No. SO00127B Revision E, dated 11/16/77; or SO-00127B-3, Revision E, dated 6/7/94, or SO-00127B-1, Revision G, dated 11/13/17, or later FAA approved revision.

1. Eligible for replacement of Cessna P/N 1754001-8, -9, -13, -14, 15M, only.

2. Parts may be used for rework of Cessna P/N 1754001-15M muffler per Installation procedure Z175.

3. SO-00127B-3 muffler eligible to replace Cessna 1754001-22 muffler on airplane serial numbers as given in Cessna Service Letter SE77-31.

4. SO-00127B-1 muffler eligible to replace Cessna P/N 9954100-9 and P/N 1754001-18.

5. Compatibility ofthis modification with other previously approved modificationsmust bedetermined by the installer.

Cessna 172 Series, 177 Series 02/5/75; 08/25/75; 8/2/76;11/29/77; 12/12/7709/27/974 10/10/74 3A12, A13CE 06/05/2019 Jim Grigg Manager, Fort Worth ACO Branch Compliance & Airworthiness Division Aircraft Certification Service 2 22 2

United States of America Department of Transportation Federal Aviation Administration Supplemental Type Certificate � 
         
             
          
  
        
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## Every issue (1)

- June 5, 2019: Amended, Current. [certificate](https://openairdocs.org/files/sha256/99/54/99543242150b1d9cc4a50e52419862dadd915f72af6fc3d2e6474b5277b9605a)

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