ECR Title: Modification of Oplev/Pcal Receiver Pylon Weldments	DCC No: E1300594-v1
Date: 11 JUL 2013
Requester: Craig Conley	Impacted Subsystem(s): AOS (Pcal)
Description of Proposed Change(s): Addition of welded Pcal Receiver Mounting Blocks to Oplev/Pcal Receiver Pylon Weldments as follows. ADD (WELD) THREE PCAL RECEIVER MOUNTING BLOCKS (D1300499-v2) (VIEWPORT FACING PANEL) (WELD-NUT, IF EXISTING, IS ON UNDER-SIDE OF PANEL) ABOVE: D1300499-v2 Pcal Receiver Mounting Blocks shown in place (to be welded) on an X-Arm pylon weldment D1001297. On Y-Arm pylon weldments D1001292, the arrangement is similar by symmetry. BELOW: The facilitated Pcal receiver module installation on a Y-Arm pylon weldment is shown. (Only the breadboard of the module is shown here. The module mounting is via the breadboard.) PCAL RECEIVER BREADBOARD
Reason for Change(s): Due to absence on the Oplev/Pcal receiver pylons of any attachment means for the Pcal receiver module, the mounting blocks D1300499-v2 were designed to be welded at three specific locations (as shown above) to facilitate a three point push-pull type mounting arrangement, adjustable for leveling and elevation, for the receiver modules.
Estimated Cost: For 6 End station pylons, total cost $1,950. Includes work crew $1000, mounts (20 pieces) $500, fixture $450.
Schedule Impact Estimate: None.
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: Start mod work week of July 22 Essential by date/event: ____________ Immediately (ASAP)
Impacted Hardware (select all that apply): Repair/Modify. List part & SNs: D1001292 (3) D1001297 (3). SNs not known. Scrap & Replace. List part & SNs:_____________________ Installed units? List IFO, part & SNs: _________________ Future units to be built	Impacted Documentation (list all dwgs, design reports, test reports, specifications, etc.): New Documents (completed)- D1300499, D1300522, D1300523, D1300524, D1300525 New Documents (to be completed)- E1300593 Documents to be revised- D1001292, D1001297, D1001325, D1001330
Disposition of the proposed change(s): The disposition of this proposed engineering change request is to be completed by Systems Engineering and indicated in the “Notes and Changes” metadata field in the DCC entry for this ECR. The typical dispositions are as follows: Additional Information Required: in which case the additional information requested is defined. The ECR requester then re-submits the ECR with the new information using the same DCC number for the ECR but with the next version number. Rejected: in which case the reason(s) for the rejection are to be given Approved Approved with Caveat(s): in which case the caveat(s) are listed TRB: the ECR is referred to an ad-hoc Technical Review Board for further evaluation and recommendation. It is the System Engineer’s (or designee’s) responsibility to organize the TRB. The System Engineer (or designee) then makes a technical decision based on the TRB’s recommendation. Links to the TRB’s documentation (charge, memos, final report, etc.) are to be added to the “Related Documents” field for this ECR. CCB: a change request for approval of additional funds or schedule impact is to be submitted to the Configuration Control Board. Links to the CCB’s documentation (CR, etc.) are to be added to the “Related Documents” field for this ECR. Concurrence by Project Management: Acknowledgement/acceptance/approval of the disposition is to be indicated by the electronic “signature” feature in the DCC entry for this ECR, by one the following personnel: Systems Scientist Systems Engineer Deputy Systems Engineer