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

SA396SW

Installation of Mitchell Automatic pilot AK118. Held by Mitchell Industries INC, which holds 37 approved modifications in all. Last revised November 16, 1964. System: other and general.

What it applies to

Kind of product
Aircraft
Design holder
Twin Commander Aircraft LLC; Twin Commander Aircraft LLC; Twin Commander Aircraft LLC; Twin Commander Aircraft LLC; Twin Commander Aircraft LLC; Twin Commander Aircraft LLC; Twin Commander Aircraft LLC
Models
500-A, 500-B, 500, 560-A, 560-E, 560, 680
Type certificates
6A1, 6A1, 6A1, 6A1, 6A1, 6A1, 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 20, 2026.