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Fiber peels off on The Face Sheet Mid Trays: SN 148, SN 159

Fiber peels off on The Face Sheet Mid Trays: SN 148, SN 159. MRB Meeting – 12 September 2005. Description and reference documentation. Description of nonconformance Fiber peels off on the face sheet Instances Detected during E.S.P.I. Incoming Suspected Root cause

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Fiber peels off on The Face Sheet Mid Trays: SN 148, SN 159

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  1. Fiber peels off on The Face SheetMid Trays: SN 148, SN 159 MRB Meeting – 12 September 2005

  2. Description and reference documentation • Description of nonconformance • Fiber peels off on the face sheet • Instances • Detected during E.S.P.I. Incoming • Suspected Root cause • Accidental Resin Drying over the very external laminate surface. • Reference NCR List • NCR n°484, 485

  3. Dispositions on the NCR • As per MRB on 13/05/05 between INFN and Plyform: • Complete assembly of tray with kapton and tungsten, then verify goodness of gluing with standard flow-chart TVAC test • 2) Inspect all face sheets and quarantine defective ones • 3) Inspect all sandwiches and quarantine defective ones • 4)Perform process controls (FVL, RCL, VCL) for face-sheets lamination on good and defective units

  4. Finding • The ESPI test was anyway successful and did not indicate any structural problem • Mid Trays 1°Mode frequency : Mean 1291 Hz, Std = 42 Hz, • Min required = 1140 Hz • Mid 148, 1°Mode frequency : 1319 Hz • Mid 159, 1°Mode frequency : 1318 Hz • E.S.P.I. Static Test (Heat source): no defect observed • The TVAC test results was was anyway successful and did not indicate any bonding problem. • The Electrical test results was was anyway successful and did not indicate problems. • The Thermal Cycle test results was was anyway successful and did not indicate problems.

  5. Electrical performance comparison • Mid 237 FRONT: 20 BAD CHANNELS; BACK: 77 BAD CHANNELS • Mid 148 FRONT: 1 BAD CHANNELS; BACK: 5 BAD CHANNELS • Mid 159 FRONT: 1 BAD CHANNELS; BACK: 5 BAD CHANNELS

  6. Rationale • From the electrical point of view Mid 237 is not conformal and it can be accepted only because the total efficiency of tower N°15 will be not affected too much, when Mid 159 and Mid 148, are well within specs. • The Hidden mechanical defect of the face-sheets doesn’t show any relevant effect on the trays behavior

  7. Proposed actions • Proposal • Use trays Mid 148 or Mid 159 on tower N°15

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