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

SA1506CE

Engine driven cabin air compressors and associated cabin pressurization controls removed. Held by Petroleum Air Transport, INC., which holds 2 approved modifications in all. Last revised April 8, 1980. System: engine.

What it applies to

Kind of product
Aircraft
Design holder
McDonnell Douglas Corporation
Models
DC-6A (USAF C-118A)
Type certificate
6A3
On this site
Douglas DC-6 17 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 20, 2026.