FAA · Supplemental Type Certificate
STC SA1399SO
Remove drain plug, Cessna Part Number MS20913-10 or MS20913-1D, from the fuel selector valve, and replace with CAV-110D (MT-1075) or CAV-110H-4D (CM-1075)
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 (4)
The STC PDF on drs.faa.gov is the authoritative document — it lists installation instructions, ICA requirements, and any limitations. Open PDF ↗