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

SA1645SW

Installation of Mitchell automatic flight system Model AK403, consisting of Century IIB autopilot with optional radio coupler. Held by Century Flight Systems INC, which holds 765 approved modifications in all. Last revised July 16, 1984. System: flight controls.

What it applies to

Kind of product
Aircraft
Design holder
Cessna Aircraft Company; Cessna Aircraft Company; Cessna Aircraft Company; Cessna Aircraft Company; Cessna Aircraft Company; Cessna Aircraft Company; Cessna Aircraft Company; Cessna Aircraft Company
Models
172D, 172E, 172F (USAF T-41A), 172G, 172H (USAF T-41A), 172I, 172K, 172L
Type certificates
3A12, 3A12, 3A12, 3A12, 3A12, 3A12, 3A12, 3A12
On this site
Cessna 172 Skyhawk 20,676 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 20, 2026.