ECR Title: ECR: Reversal of wedge orientation for hanging PR3-01 in H1.	DCC No: E1201105-v1
Date: 12 Dec 2012
Requester: Norna Robertson	Impacted Subsystem(s): SUS, IO
Description of Proposed Change(s): We propose to hang the optic PR3-01 in H1 with the thick end of the wedge at the top. This is the opposite of the design direction of the wedge as captured in E0900342. That document states arrow at top, where the arrow is at the thin end of the wedge as per substrate drawing D080662.
Reason for Change(s): This optic was damaged (small cracks) when a metal prism was knocked off. Options for how to proceed were discussed in T1200494. We concluded that the best way forward was to hang the optic upside down relative to the design orientation to avoid regluing a prism on a weakened area. It was confirmed with the IO group that this has no negative implications for the position of any transmitted beam and associated baffling since there is no appreciable transmitted beam from this optic and hence no baffling is used.
Estimated Cost: no further costs involved.
Schedule Impact Estimate: We estimated a few days longer to carry out the gluing than the other options considered (see T1200494).
Nature of Change (check all that apply): Safety Correct Hardware Correct Documentation	Improve Hardware Improve/clarify Documentation Change Interface Change Requirement
Importance: Desirable for ease of use, maintenance, safety Desirable for improved performance, reliability Essential for performance, reliability Essential for function Essential for safety	Urgency: no urgency desirable by date/event: ____________ Essential by date/event: ____________ Immediately (ASAP)
Impacted Hardware (select all that apply): Repair/modify. List part & SNs: PR3-01____________________ Scrap & Replace. List part & SNs:_____________________ Installed units? List IFO, part & SNs: _To be installed in HAM2 at LHO________________ Future units to be built	Impacted Documentation (list all dwgs, design reports, test reports, specifications, etc.): D0901086, possibly others?
Disposition (to be completed by Systems Engineering): TRB CCB Approved Additional information required. Define: [Requester re-submits with new information with the same DCC E-number for the ECR but the next version number.] Concurrence by Project Management: (Acknowledged Electronically in DCC) Project Systems Engineer: Dennis Coyne Project Systems Scientist: Peter Fritschel