On Tuesday the fluid level in the EndY HEPI Reservoir was found to be 1/2" lower in just one week.  As I suspected, a leaking schrader valve was the problem.  All seven accumulators on the EndY system are at the same pressure as last week except the one on PRESS2 at the pump station.  It was exactly zero.  After charging, the saliva test showed a very suttle leak and tightening the schrader valve was repeatedly not successful.  The valve was replaced and it seems to be holding now.

This accumulator is charged to 78 psi and losing this one unit is responsible for the entire 1/2" fluid drop.  I can imagine the relation between accumulator pressure and fluid level in the reservoir is maybe not linear.  But maybe close, so at the ends, to maintain the spec of 60-93% accumulator charge, a fluid drop of only ~3/16" could be too much.  But this would be the case if it is only one accumulator.  Many could be at 80% say and we might hit the 1/4" fluid drop threshold.

Let's make this easy: if there is no observed fluid drop, the accumulators are likely fine.  If the level drop is more than 1/8", that is likely outside the typical temperature fluctuations and the system should be checked for actual fluid leaks and accumulator charge loss.

Given that this accumulator is before the second laminar flow resistor and the 3rd accumulator on the pump station, and, remember there are two more accumulators at the chamber before the HEPI Actuators, I suspect this one accumulator loss will have had little affect on PS pressure fluctuations coupling into platform motion.  But, that will be determined by data rather than supposition--so data to come.