Aircraft STC directory
Textron Aviation 421C STCs
The Jun 30, 2026 FAA DRS snapshot contains 17 selected supplemental type certificates with status Current whose public applicability data names the Textron Aviation 421C. Use it to identify modification scope and recorded holders—not to determine serial-number effectivity, compatibility, installation approval, or commercial availability.
Modification demand surface
Recently revised 421C STCs
Showing the 17 most recently revised records. Each entry links to the FAA source and separates public approval data from private commercial claims.
Install Cleveland conversion kit P/N 199-76.
FAA holder: Kaman Corporation Aircraft Wheel and Brake LLC
Installation of the KFC 230 Aerocruze Automatic Flight Control System (FCS) upgraded from KFC 200 FCS.
FAA holder: Honeywell International Inc. (Bendix King)
Installation of Bendix/King KFC 225 Automatic Flight Control System. For Model 421C, serial numbers 421C0401 and after.
FAA holder: Honeywell International Inc
Installation of Bendix/King KMD 550/850 Multi-Function Display, with optional KLN 94 Global Positioning System, KGP 560 General Aviation Enhanced Ground Proximity Warning System, RDR 2000 Weather Radar System and KMH 880 Multi-Hazard Awareness System or KTA 870 Traffic Awareness System.
FAA holder: Honeywell International Inc
Installation of King KFC 250 flight control system (3 axis) using 3-inch or 4-inch indicators.
FAA holder: Honeywell International Inc
Installation of King KAS 297 Altitude Selector Option.
FAA holder: Honeywell International Inc
Fabrication and Installation of Dahlia Doubler.
FAA holder: Fliegen Works Inc.
Fabrication and Installation of Panida Doubler.
FAA holder: Fliegen Works Inc.
Fabrication and Installation of Panida Doubler.
FAA holder: Fliegen Works Inc.
Installation of a Strobe Light System.
FAA holder: Reds Aircraft Service Inc.
Installation of an S-TEC 01326 Digital Flight Control System (DFCS).
FAA holder: S-TEC Corporation
Installation of a Taxi Light System.
FAA holder: Reds Aircraft Service, Inc.