# STC SA2721WE

- Type: Supplemental type certificate
- Status: Current, Reissued
- Holder: United Aeronautical Corporation, United States
- Description: Install external retardant tank.
- Applied: May 14, 1972
- Status date: April 15, 2015
- Product: Aircraft, Large Airplane
- Certification basis: Part 21
- Data sheets: [TCDS 6A4](https://openairdocs.org/tcds/6A4)
- Certificate PDF: https://openairdocs.org/files/sha256/7e/d1/7ed159c5766b75b272d14932c1df7f53902d2879db817b1405e93b6f0a3e13c8
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/C1B3C1DE337B51BB86257E2A00590807.0001
- DRS record last changed: December 6, 2025
- Page: https://openairdocs.org/stc/SA2721WE

## ADs that name it (0)

None.

## Approved models (1)

- The Boeing Company DC-6B ([TCDS 6A4](https://openairdocs.org/tcds/6A4))

## 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 This certificate has been reissued to replace the original certificate reported as lost.

This Certificate issued to United Aeronautical Corporation 7360 Laurel Canyon Blvd.

North Hollywood, California 91605 Part 4b of the Civil Air Regulations.

(See Type Certificate Data Sheet 6A4) Original Product Type Certificate Number :

6A4 The Boeing Company DC-6B Description of Type Design Change: Install external retardant tank in accordance with FAA sealed Aero Union Drawing List No. AU3100. Aircraft must be loaded in accordance with FAA approved Aero Union Weight and Balance Report No. W B001 dated June 30, 1973, and operated in accordance with FAA approved Aero Union Supplement No. MS001 dated October 5, 1977, or later FAA approved revision to Airplane Flight Manual 19501(UAL) and 14748(TAI). Applies to UAL aircraft serial numbers 44893 through 44902, 45131 through 45137 and 45491 through 45494 onl. Applies to TAI aircraft serial numbers 43833, 43834, 44696, and 44697 only.

Limitations and Conditions : The approval of this change in type design applies basically to the DC -6B airplane only. This approval should not be extended to other aircraft of this model on which other previously approved modifications are incorporated unless it is determined by the installer that the interrelationship between this change and any of those other previously approved modifications will introduce no adverse effect upon the airworthiness of that aircraft. This determination should include consideration of significant changes in weight distribution such as increase in the fixed disposable weight (including ballast) in th e fuselage. If the holder agrees to permit another person to use this certificate to alter a product, the holder shall give the other person written evidence of that permission.

his certificate and the supporting data which is the basis for approval shall remain in effect until surrendered, suspended, revoked or a termination date is otherwise established by the Administrator of the Federal Aviation Administration Date of application : May 14, 1972

Date of issuance : July 11, 1973

Date reissued : April 15, 2015

Date amended : October 5, 1977

(Signature) Supervisor, Technical and Administrative Support Staff Los Angeles Aircraft Certification Office (Title)

## Every issue (1)

- April 15, 2015: Reissued, Current. [certificate](https://openairdocs.org/files/sha256/7e/d1/7ed159c5766b75b272d14932c1df7f53902d2879db817b1405e93b6f0a3e13c8)

---
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.