While checking operation of the M9 and M20 beam blockers earlier this week, a strange noise was noticed coming from the T2 cooling package area.  It is a squealing sound that starts when M9BB, M20BB, or T2 profile monitor are actuated and continues for approximately 30 seconds, then stops.  The source was eventually narrowed down to somewhere on the air supply line coming from the air amplifiers on the south mezanine.  When the air amplifiers are adjusted below ~95psi, the noise stops (the standard setting is 110psi).  A 20psi Nupro check valve on the line was suspected to be causing the noise.  It was removed, rebuilt, and reinstalled, but there was no improvement.

A few of the blocks directly east of the T2 cooling package must be removed so we can have access to the lines in that area.  We will continue our investigation next week.