For those who might be interested in the Garmin 175, the STC and AML are here.
https://rgl.faa.gov/Regulatory_and_Guidance_Library/rgstc.nsf/0/62018D7400B0F8CD862585AE004277E9?OpenDocument&Highlight=%20sa02636se
Approval is for 3A18 — Interceptor Aircraft Inc — 200 3A18 — Interceptor Aircraft Inc — 200A 3A18 — Interceptor Aircraft Inc — 200B 3A18 — Interceptor Aircraft Inc — 200C 3A18 — Interceptor Aircraft Inc — 200D 3A18 — Interceptor Aircraft Inc — 400
The spool valve is the box mounted to the firewall with all the hydraulic lines attached. The front safety wired nut has a spring and a ball fitting.