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

ST00038WI

Installation of Bendix/King CAS-81 traffic alert and collision avoidance system (TCAS II) and MST-67A Mode S transponder system. Held by Duncan Aviation, INC, which holds 158 approved modifications in all. Last revised March 21, 1994. System: instruments and avionics.

What it applies to

Kind of product
Aircraft
Design holder
Learjet Inc.; Learjet Inc.; Learjet Inc.; Learjet Inc.
Models
Learjet 36A, Learjet 36, Learjet 35A (C-21A), Learjet 35
Type certificates
A10CE, A10CE, A10CE, A10CE
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.