Non Conformance Report Nr. 002

24^th November 2003

Report:

Step number 215-00 - X axis Low Level Signature post random test 0dB.

Run stopped at 102.5 Hz due to the presence of two peaks

below 100 Hz (68 Hz, 87Hz) in the response of channel 1 (reference

accelerometer for X axis test) as shown in attachment (figure

“Low_Level_acc1.jpg”).

Furthermore a reduction of the frequency of the first mode was observed

during the full level random vibration random as shown in figure “random0db_acc1.jpg” in attachment.

Post-Test Inspection performed:

- Torque checked on the 32 M10 screws on the fixture: no change found;

- Tapping on the sidewalls: no apparent hollow sounds;

- Lift device attached to the tower and then to the crane;

- 32 M10 unscrewed starting from -Y sidewall in clockwise direction;

- Tower lifted above the slip table;

- Visual inspection of the bottom tray and flexures from below without

de-mating the flex cables form the test configuration showed no signs of

breakage or disturbance of the torque stripes of the screws;

- Check of the adapter plate with kapton tape: no presence of powder or

debris;

- Tower placed back on the adapter again waiting for further disposition

Action:

- Inform SLAC Project Office of the observed anomaly – completed;

- Inform INFN-Pisa to generate an inspection plan – completed.

Status:

Open