Was going flying w/CFI: a zillion T&G's at a quiet valley airport. Tule fog and VLIFR scrubbed that. Temp probes are hooked up to the correct cylinders on Dynon EMS. (Tested w/heat gun briefly blowing on probes.)
Continued removing panels from cockpit and opened up the baggage bulkhead. Tested static line from the tube running down from the ganged ADAHRS to tee between aft static ports and alt static switch in panel. Did not hold vacuum at all.
Established the ADAHRS units and push-on (PO) fittings weren't leaking: directly coupled: syringe->rubber MAP hose->1/4" Al tube->PO fitting->ADAHRS unit. Blank off one arm of the tee for primary ADAHRS. Secondary ADAHRS was good; primary wasn't. OK, leak in the unit or the PO fitting? Moved tee fitting to secondary ADAHRS; with fresh sealant on the pipe threads, it was good too. Oh snap, leak in primary ADAHRS? No! Put tee back on (with fresh sealant) and it was rock solid.
Hooked up plastic hose between the primary's tee and secondary's elbow, pulled vacuum tee’s open port: massive leak is back. Replaced the plastic hose with 1/4" Al tube—NO leak. Hooked up the plastic tube running down to fore-aft static line tee, pulled off static-side tube, pulled vacuum on static side, (this tested forward line and alt static valve): pulled vacuum and altitude 3k’ above field level was steady.
Removed ADAHRS fittings for pitot and AOA to put fresh sealant on them too, just in case. May have disturbed the pitot lines: a quick pitot test didn’t hold pressure! May wind up replacing more plastic lines around the ADAHRS units with Al tubing. End this nonsense for good!