15. On the outside of the helmet shell, in-
stall the left receiver mounting block,
and jaw assembly over the end of the
screw. (See Figure 4-63.) Finger-
tighten screw so that receiver can be
adjusted as necessary.
Ensure that the thicker side of the tapered re-
ceiver mounting block is positioned toward
the helmet shell edge beading.
When installing screws, leave the screw loose
enough to allow the jaw receiver to pivot so
that proper alignment can be achieved.
Figure 4-63. Bayonet Receivers and
16. Reinstall the earcup and have the operator/wearer don the helmet. Insert the left
bayonet into the receiver installed in step 15. Have the operator/wearer hold the
mask so that it fits properly.
17. Position the left jaw receiver assembly and the left receiver mounting block until
the correct position is attained.
Mark the position of the bottom hole.
18. Remove mask, and have the operator/wearer remove the helmet.
19. Pivot the jaw assembly and the receiver mounting block to access the marked
hole for drilling.
20. Detach the earcup from the retaining pad, and pull the earcup out of the way.
This will prevent damage during drilling.
21. Center punch the hole marked in step 17.
Wear safety goggles (Item 10, Appendix E) when drilling the helmet shell.
Before drilling the helmet shell, ensure proper location of receivers.
This is important because the receivers are only slightly adjustable
once they are attached to the helmet.
When drilling the helmet shell, hold the drill perpendicular to the
helmet shell to prevent damage to the shell.
22. Place helmet on table. Using an electric drill (Item 9, Appendix B) and a #27 drill
bit (Item 7, Appendix B), drill the hole marked in step 17. Use a small rattail file
to remove any rough edges.
23. Install the outer 6-32 x 9/16 pan-head screw, #6 lockwasher, bayonet receiver
backplate, left receiver mounting block, and jaw assembly.
24. Remove the receiver.
25. Remove the inside mounting screw attaching the boom and microphone to the