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

SA1-39

Recovering of wings with metal skin, .020 inch 24ST alclad, except ailerons. Held by Boone County Aviation, INC. Last revised June 4, 1970. System: airframe structure.

What it applies to

Kind of product
Aircraft
Design holder
The Cessna Aircraft Company
Models
140
Type certificate
A-768
On this site
Cessna 140 1,839 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 21, 2026.