The T2 Collimator A flow meter signal (B1A:T2:FGCOLA) began fluctuating and occasionally reading 0gpm on Sunday Oct 25 causing BL1A trips and machine down time.

On the maintenance day today (Tues Oct 27), the T2 package was uncovered and the T2 Col. A flow meter was opened.  No unusual deposits were observed as seen recently with other flowmeters for BL1A magnets on the CuALCW system.  Some minor wear was observed on the dowel pin shaft, and the paddle wheel didn't spin quite as freely as when new.  A small amount of reddish/brown film (rust?) was seen on the internal SS faces.  The faces were wiped clean and new dowel pin, paddle wheel and o-ring were installed.

The pin, paddlewheel, and o-ring were also replaced for B1A:T2:FGCOLB (no wear observed on old pin) and B1A:T2CS:FGTGT (some wear observed on pin, more than Col. A).  They were not replaced on B1A:T2CS:FGSEC or B1A:T2CS:FGDEM at this time, as neither of these has a noisy signal, and neither can cause trips in the control system.

After all paddlewheels were re-installed and the system restarted, the flowmeters behaved as expected.  The fluctuations that occurred on Sunday were not happening this morning prior to the change, so we're unsure at this point if this has solved the problem.  StripTool was used before and after the change to observe fluctuations in the readbacks, and no noticeable difference was observed.

During testing of the flow meters we observed that B1A:T2:SVCOLB seemed to not respond one of the times it was commanded to close, and one or two other times it seemed to close after a few seconds delay.

Note: All T1 and T2 paddlewheels, pins, and o-rings were changed earlier this year.  They're scheduled to be replaced every 2 years as per the T1/T2 maintenance plan.