FAA · Supplemental Type Certificate
STC SA2991SO
Installation of a replacement coalescer filter, P/N 21D10 or 21D10-1, or 21BC125..
What is an STC?
A Supplemental Type Certificate authorizes a major modification or alteration to an FAA-certificated aircraft. STCs are how operators legally install new avionics, change fuel systems, add floats, swap engines, etc. — every change beyond a minor modification needs one.
Applicable aircraft (24)
- A6WE McDonnell Douglas Corporation · DC-9-11
- A6WE McDonnell Douglas Corporation · DC-9-12
- A6WE McDonnell Douglas Corporation · DC-9-13
- A6WE McDonnell Douglas Corporation · DC-9-14
- A6WE McDonnell Douglas Corporation · DC-9-15
- A6WE McDonnell Douglas Corporation · DC-9-15F
- A6WE McDonnell Douglas Corporation · DC-9-21
- A6WE McDonnell Douglas Corporation · DC-9-31
- A6WE McDonnell Douglas Corporation · DC-9-32
- A6WE McDonnell Douglas Corporation · DC-9-32 (VC-9C)
- A6WE McDonnell Douglas Corporation · DC-9-32F
- A6WE McDonnell Douglas Corporation · DC-9-32F (C-9A)
- A6WE McDonnell Douglas Corporation · DC-9-32F (C-9B)
- A6WE McDonnell Douglas Corporation · DC-9-33F
- A6WE McDonnell Douglas Corporation · DC-9-34
- A6WE McDonnell Douglas Corporation · DC-9-34F
- A6WE McDonnell Douglas Corporation · DC-9-41
- A6WE McDonnell Douglas Corporation · DC-9-51
- A6WE McDonnell Douglas Corporation · DC-9-81
- A6WE McDonnell Douglas Corporation · DC-9-82
- A6WE McDonnell Douglas Corporation · DC-9-83
- A6WE McDonnell Douglas Corporation · DC-9-87
- A6WE McDonnell Douglas Corporation · MD-88
- A6WE McDonnell Douglas Corporation · MD-90-30
Certification basis — 14 CFR
The STC PDF on drs.faa.gov is the authoritative document — it lists installation instructions, ICA requirements, and any limitations. Open PDF ↗