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

SA1431WE

Installation of rudder trim system. Held by Robertson Aircraft CORP, which holds 2 approved modifications in all. Last revised April 2, 1978. System: flight controls.

What it applies to

Kind of product
Aircraft
Design holder
The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company; The Cessna Aircraft Company
Models
172H (USAF T-41A), 172M, 172, 172A, 172B, 172C, 172D, 172F (USAF T-41A), 172G, 175B, 175C, 175A, 150E, 150F, 150G, 180G, 180D, 180E, 180A, 180C, 180H, 180F, 180B, 177
Type certificates
3A12, 3A12, 3A12, 3A12, 3A12, 3A12, 3A12, 3A12, 3A12, 3A17, 3A17, 3A17, 3A19, 3A19, 3A19, 5A6, 5A6, 5A6, 5A6, 5A6, 5A6, 5A6, 5A6, A13CE
On this site
Cessna 150 7,993 registered
Cessna 172 Skyhawk 20,675 registered
Cessna 175 Skylark 925 registered
Cessna 177 Cardinal 2,158 registered
Cessna 180 Skywagon 2,605 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.