SA4-329
Step kit added to fore and aft cargo door. Held by National Aircraft CORP, which holds 3 approved modifications in all. Last revised January 1, 1960. System: airframe structure.
What it applies to
- Kind of product
- Aircraft
- Design holder
- McDonnell Douglas Corporation; McDonnell Douglas Corporation; McDonnell Douglas Corporation
- Models
- DC-7 Series, DC-6 Series, DC-6B (Navy R6D-1Z)
- Type certificates
- 4A10, 6A3, 6A4
- On this site
- Douglas DC-6 17 registered
Douglas DC-7 5 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.