The U.S. aircraft register, updated daily
Who holds what · as the FAA records the name

National Aircraft CORP

Holds 3 approved modifications, most of them for the Douglas DC-6. FAA spelling: National Aircraft Corp.

Approved modifications 3 · newest first

Douglas DC-6 3Douglas DC-7 3
1960-01-01SA4-329 · Step kit added to fore and aft cargo door. · DC-7 Series, DC-6 Series, DC-6B (Navy R6D-1Z)
1960-01-01SA4-330 · Step kit added to fore and aft cargo door. · DC-7 Series, DC-6 Series, DC-6B (Navy R6D-1Z)
1960-01-01SA4-328 · Step kit added to fore and aft cargo door. · DC-7 Series, DC-6 Series, DC-6B (Navy R6D-1Z)

Source: FAA Dynamic Regulatory System (type certificate data sheets, supplemental type certificates, technical standard order authorisations). An organisation's name is as the FAA spelled it on each record; related spellings are separate pages.