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

SA1734GL

Installation of freon air conditioning system. Held by Basler Turbo Conversions INC., which holds 9 approved modifications in all. Last revised August 16, 1994. System: heating, ice protection and utility systems.

What it applies to

Kind of product
Aircraft
Design holder
McDonnell Douglas Corporation; McDonnell Douglas Corporation; McDonnell Douglas Corporation; McDonnell Douglas Corporation
Models
DC3A-S1C3G, DC3D-R-1830-90C (Army C-117A), DC3A-SC3G, DC3A-S4C4G
Type certificates
A-669, A-669, A-669, A-669
On this site
Douglas DC-3 155 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 7, 2026.