(1) DOCUMENT CHANGE NOTICE (DCN):

DCN No. E1000388-v1


(2) INFORMATION:

DOCUMENT No.       TITLE                                            

    * D1000631-v2: aLIGO TOP ADD MASS TOWER
    * D1000632-v2: aLIGO TOP ADD MASS BAR
    * D1000633-v2: aLIGO ADD TOP MASS TEE
    * D1000656-v2: aLIGO TOP ADD MASS SIDE SLOTTED BAR


(3) CHANGE DESCRIPTION (FROM / TO):

D1000631:
* All reference dimensions to CG removed for clarity.

D1000632:
* All reference dimensions to CG removed for clarity.
* View A-A added, showing 2 added #10-24 blind tapped holes.
* 4 holes
  -were- 1/4-20 drilled thru & tapped .50 deep
  -are-  .266 dia. thru all, c'bore .390 dia x .30 deep

D1000633:
* All reference dimensions to CG removed for clarity
* At zone C-1
  Dim .94 -was- 1.20
  Dim 2.78 -was- 2.70
  Dim 6.81 -was- 6.73
* At zones A-1 thru A-4
  Dim 2.63 -was- 2.55
  Dim 1.25 dia. -was- 1.27 dia.
  4 holes drilled thru & tapped 1/4-20 x .38 deep, etc. -were- .281 THRU ALL
* At zones C-5 thru C-8
  New cut features are shown in added views
* At zones C-5
  6 #10-24 X .30 deep blind tapped holes added
* Noted weight -is- 9.889#, -was- 9.846#

D1000656:
* All reference dimensions to CG removed for clarity
* Part redesigned for adjusted mass properties. Noted weight -is- 1.525#, -was- 2.232#.


(4) REASON FOR CHANGE:

Clearence deficiencies necessitated changes to D1000633. Weight & CG requirements
needed to be maintained, necessitating changes to D1000631, D1000632, & D1000656.


(5) SIGNATURES REQUESTED:

Dennis Coyne
Ken Mailand


(6) DCN DISTRIBUTION:

Dennis Coyne
Ken Mailand


(7) NOTES: