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

SA3890WE

Installation of Wright R-1820-40, -60, -71, -87 engine and Hamilton Standard 33D50 or 43D50 constant speed propeller. (S2R RESTRICTED CATEGORY). Held by Steward-Davis, INC, which holds 4 approved modifications in all. Last revised May 18, 1979. System: propeller.

What it applies to

Kind of product
Aircraft
Design holder
Ayres Corporation
Models
S2R
Type certificate
A4SW
On this site
Ayres Corporation S-2 244 registered
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 22, 2026.