ST974SO
Installation of extra crew seating and air distribution system. Held by Bellomy-Lawson Aviation INC, which holds 10 approved modifications in all. Last revised March 29, 1978. System: other and general.
What it applies to
- Kind of product
- Aircraft
- Design holder
- McDonnell Douglas Corporation; McDonnell Douglas Corporation
- Models
- DC-6A (USAF C-118A), DC-6B (Navy R6D-1Z)
- Type certificates
- 6A3, 6A4
- 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 7, 2026.