The U.S. aircraft register, updated daily
Approved modifications · supplemental type certificate · current · amended

SA924NW

Installation of Hartzell HC-B3TN-5K/T-10178-B13Q propellers on AiResearch Model TPE-331-1-151K in accordance with Pacific Propeller, Inc. Master Drawing List 76025. Held by Pacific Propeller International LLC, which holds 27 approved modifications in all. Last revised June 30, 2005. System: propeller.

What it applies to

Kind of product
Aircraft
Design holder
Twin Commander Aircraft Corporation
Models
680-W
Type certificate
2A4
The FAA's record
On the FAA's site

What an approved modification is

A supplemental type certificate is the FAA's approval of a change to a certified design: a new engine or propeller, avionics, an autopilot, floats, a parachute, a larger fuel tank, an ice-protection kit. The company holding it may sell the kit and the paperwork to owners of the listed models; the modification then becomes part of that aircraft's record. The FAA's list says what was approved and for which models, not how many aircraft carry it.

Source: FAA supplemental type certificates (Dynamic Regulatory System). Register counts from the FAA register of October 7, 2026.