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

SA4219WE

Installation of DTL-1000, -1001 and/or -1002/3 autopilot adapters for the Edo-Aire Mitchell Century III autopilot. Held by Kettler Douglas L, which holds 6 approved modifications in all. Last revised September 2, 1980. System: flight controls.

What it applies to

Kind of product
Aircraft
Design holder
Twin Commander Aircraft Corporation; Twin Commander Aircraft Corporation; Twin Commander Aircraft Corporation; Twin Commander Aircraft Corporation
Models
500-B, 500-A, 500-U, 500-S
Type certificates
6A1, 6A1, 6A1, 6A1
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.