# STC SA3539WE

- Type: Supplemental type certificate
- Status: Current, Reissued
- Holder: Northrop Grumman Systems Corporation, United States
- Description: Installation of single, palletized Litton LTN-51 or LTN-72 Inertial Navigation System (707-320C Series)
- Applied: November 9, 1977
- Status date: April 12, 2016
- Product: Aircraft, Large Airplane
- Certification basis: Part 21
- Data sheets: [TCDS 4A26](https://openairdocs.org/tcds/4A26)
- Certificate PDF: https://openairdocs.org/files/sha256/0c/09/0c09eb8aa326337b68c86ada54c821b62c33ed86b317cb43ebe2ebd6959f94d1
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/DE319EAF0296A78786257FA2006DC3C2.0001
- DRS record last changed: December 6, 2025
- Page: https://openairdocs.org/stc/SA3539WE

## ADs that name it (0)

None.

## Approved models (3)

- The Boeing Company 707-300 Series ([TCDS 4A26](https://openairdocs.org/tcds/4A26))
- The Boeing Company 707-300B Series ([TCDS 4A26](https://openairdocs.org/tcds/4A26))
- The Boeing Company 707-300C Series ([TCDS 4A26](https://openairdocs.org/tcds/4A26))

## 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.

FAA Form 8110-2(10-68) Page 1 of 2 Number SA3539WE This Certificate issued to Northrop Grumman Systems Corporation 21240 Burbank Blvd.

Woodland Hills, CA 91367-6675

Part 4b of the Civil Air Regulations (For certification basis see Type Certificate Data Sheet 4A26.)

4A26

Boeing

707-320C Series Description of Type Design Change : Installation of single, palletized Litton LTN-51 or LTN-72 Inertial Navigation System in accordance with FAA approved L itton Top Drawing No. 452853- 09 Revision “A” or later FAA approved revision. Litton Airplane Flight Manual Supplement for Boeing 707-300, -400, -300B, -300C Series, FAA approved on December 20, 1977, or later FAA approved revision is required as part of this installation.

Limitations and Conditions : This approval should not be extended to other specific airplanes of these models 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. A copy of this certificate must be maintained as part of the permanent records for the modified aircraft. 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: November 9, 1977

Date of issuance: December 20, 1977

Date reissued: April 12, 2016

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

NOTE:

**DO NOT DELETE THIS PAGE.**

**DO NOT ADD ANY DATA TO THIS PAGE.**

**THIS PAGE IS FOR PAGE NUMBERING PURPOSES, PLEASE DISCARD PRINTED COPY.**

## Every issue (1)

- April 12, 2016: Reissued, Current. [certificate](https://openairdocs.org/files/sha256/0c/09/0c09eb8aa326337b68c86ada54c821b62c33ed86b317cb43ebe2ebd6959f94d1)

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