The integrated chin/nape strap assembly is a patented device that threads through the helmet to form a continuous loop smaller than the smallest head circumference. The design permits simultaneous adjustment of the chinstrap and the nape strap; cross straps in the nape area respond to chinstrap adjustments to provide a snug, stable, and comfortable fit.

the integrated chin/nape strap is presently featured in helmets such as the HGU-55/P, HGU-85/P (Night Attack) helmet, and the HGU-68/P (TACAIR) helmet. The HGU-68/P & HGU-87/P helmets with the integrated chin/nape strap assembly have been successfully windblast-tested at 600 knots. 

Conversion Steps
1) Remove existing chinstrap and nape strap. 
2) Remove earcups, communication cord, and TPL liner. 
3) If the helmet is Combat Edge equipped, remove the bladder & hardware. 
4) Align template with the existing chin strap and nape strap holes. Using a pencil and the proper-size template, mark each side of the helmet shell with the new hole locations. 
5) Using a center punch, indent the shell at the new hole locations. 
6) Using a 1/16" bit, drill a pilot hole in each location. Exercise care when drilling through pile (inside helmet cloth). 
7) Using a 1/4" bit, finish drilling the three holes. 
8) Using a flexible straight edge, draw two lines connecting the outer edges of the 3 chinstrap holes in the front of the shell. 
9) Elongate the three chinstrap holes for eyelet installation using a small saw blade to cut slot. File as necessary until eyelet fits. 
10) Insert one side tab of plastic strap grommet into slot in shell from outside, gently work two small end tabs into shell, and then work the final side tab through slot in shell. 
11) Fill old nape strap hole with epoxy. Allow epoxy to harden properly before proceeding. 
12) Trim pile fastener or leather as necessary to ensure eyelet slot is fully accessible. 
13) Re-adhere pile fastener or leather to shell, this is the cloth inside that the earcups Velcro to. 
14) Trim the aft lower corners of the helmet liner as required for attachment of the nape straps and nape pad eyelets. 
15) Insert left and right nape straps through the eyelets from front to rear. 
16) Insert nape straps through nape pad. 
17) Install chin/nape straps with attaching hardware. 
18) If Combat Edge kit was removed- reinstall at this time. 
19) Install helmet liner (TPL, etc). 
20) Route ear-to-ear cord between liner and edgeroll and install earcups. 
21) Have crewmember don helmet. 
22) Adjust height of nape strap pad by loosening attaching hardware, rotating nape strap pad strap(s) up or down, and tightening hardware. 
23) Adjust nape strap tension using nape strap clamps on the left and right nape straps.

Template

Source: CSA