(Gray, Kissel, Thomas)
Per Mainteance Day procedure, SEI_CONF was transitioned to SC_OFF_NOBRSXY. Went back to WINDY a little early 11:42amPDT. Noticed the SEI_CONF guardian node was transitioning in/out of being in a green NOMINAL state. Looked upstream and saw that the ETMx ST1 node was also not GREEN in its NOMINAL State. This eventually had us look at BRS (on Patrick's suggestion), and then Jeff brought up the BRS Health ndscope and noticed odd behavior (i.e. weird "heart beat" behavior for the BRS EX INMON signal is shown in the top plot in the attached plots).
To help correct the situation, we took SEI_CONF to WINDY_NO_BRSX. Jeff hit the DISABLE button for BRSx. And then we monitored the BRS Health ndscope. After DISABLING the damping, the INMON signal changed to a more normal-looking oscillation (vs. the heart beat). We then monitored for awhile; the resonant frequency for BRS is in the millihertz range, so it takes on the order of minutes to see an oscillation or two.
Will continue monitoring and see how we should operate BRSx post-Maintenance.
With SEI_CONF still in the WINDY_NOBRSX state, we re-ENABLED the damping for BRSx. You can see it looked big for part of a cycle (I almost DISABLED!), but luckily after a cycle or two, the INMON BRSx signal (orange) damped out pretty well.
The attached plots show BRS Health for a few hours and then there is a zoomed in spot of when the damping was re-ENABLED. The time between the two vertical cursors is when we running with no BRSx damping.
Once we had a lockloss, and since BRSx looked nice, I took the SEI_CONF back to the nominal WINDY state.
