# STC ST557SO

- Type: Supplemental type certificate
- Status: Current, Issued
- Holder: Eastern Airlines, Inc, United States
- Description: Installation of 99 passenger interior arrangement.
- Status date: October 6, 1973
- Product: Aircraft, Large Multi-Engine
- Certification basis: Part 21
- Data sheets: [TCDS A6WE](https://openairdocs.org/tcds/A6WE)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/A0991233898B878085256CC300036088.0001
- DRS record last changed: December 6, 2025
- Page: https://openairdocs.org/stc/ST557SO

## ADs that name it (0)

None.

## Approved models (1)

- McDonnell Douglas Corporation DC-9-31 ([TCDS A6WE](https://openairdocs.org/tcds/A6WE))

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.