# STC SP1521SO

- Type: Supplemental type certificate
- Status: Current, Amended
- Holder: Northwest Propeller Services Inc., United States
- Description: Install Northwest Propeller Service Counterweight Thrust Bearings in place of the Hamilton Standard Counterweight Thrust Bearings
- Applied: April 7, 1983
- Status date: August 6, 2003
- Product: Propeller
- Certification basis: Part 21
- Data sheets: [TCDS P-257](https://openairdocs.org/tcds/P-257), [TCDS P-206](https://openairdocs.org/tcds/P-206)
- Certificate PDF: https://openairdocs.org/files/sha256/04/dc/04dcdfed92bc60b6670f9aaeb90bd9408dc26baee50f77e485dafa89a04a1277
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/D901757C036E52F686256D8A005B9173.0001
- DRS record last changed: December 5, 2025
- Page: https://openairdocs.org/stc/SP1521SO

## ADs that name it (0)

None.

## Approved models (2)

- Hamilton Standard Division 12D40 ([TCDS P-257](https://openairdocs.org/tcds/P-257))
- Hamilton Standard Division 2D30 ([TCDS P-206](https://openairdocs.org/tcds/P-206))

## What the certificate says

This is OCR from the scanned FAA certificate. OCR can misread letters and numbers.

United States of America Book Department of Transportation Federal Aviation Administration sent to Connie Supplemental Type Certificate Number: SP152150 This certificate issued to: Northwest Propeller Service, Inc.

16709 Meridian Street E., Unit 3 & 4 Puyallup, WA 98373 Part 14 of the Civil Air Regulations.

Original Product -Type Certificate Number: P-206-5 and P-257-6 Make: Hamilton Standard Model: 2D30, 12D40, 3D40 Description of Type Design Change: Install Northwest Propeller Service Counterweight Thrust Bearings in place of the Hamilton Standard Counterweight Thrust Bearings, in accordance with FAA sealed Northwest Propeller Service Master Drawing List No. NPS-8300, Revision A, dated May 31, 2003, or later FAA approved revision.

Limitations and Conditions: This approval should not be extended to other propellers 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 propeller. A copy of this Certificate must be maintained as part of the permanent records for the modified propeller.

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.

stablished by the let until surrendered, suspended, revohed, or a termination date is otherwise established by the Administrator of the Federal Aviation Administration .

Date of Application: April 7, 1983 Date Reissued: May 1, 1984; January 5, 1999 Date of Issuance: December 5, 1983 Date Amended: October 21, 2002; August 6, 2003 FEDERAL AVIATION rection the . Samin (Signature) TOMINIST RATION Acting Manager, Seattle Aircraft Certification Office (Title)

## Every issue (1)

- August 6, 2003: Amended, Current. [certificate](https://openairdocs.org/files/sha256/04/dc/04dcdfed92bc60b6670f9aaeb90bd9408dc26baee50f77e485dafa89a04a1277)

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