ACH Sizing Assignment

Objective
To ensure proper protection from both blunt and ballistic impacts ACH sizing and fit most be correct. The following outlines proper ACH sizing and fitting guidelines based on Gentex Corporation TP0271 REV. 2 (February 2007), Specialty Defense TM2412 (September 2006, Measurer’s Handbook: U.S. Army Anthropometric Survey 1987-1988 (Technical Report: Natick/TR-88/043), Department of the Army Operator’s Manual for Advance Combat Helmet (TM 10-8470-204-10), and 3M combat helmet sizing instructions.
Procedures
1. Equipment
1.1. Outside calipers
1.2. Flexible tape measure
1.3. Chair
1.4. Recording device and recording tables
1.5. Sizing chart
2. Pre-test Calibration
2.1. Equipment calibration procedures
2.2. Perform calibration in accordance with DOT spec TP-218-06, 8
2.2.1.1. Ruler

If crown pad does not touch the top of the individuals head even after repositioning and adequately tightening the retention straps before reassigning an individual to a larger ACH shell size
7.2.1.4.1.1.1. In human factors testing, we will not allow for adjustment of the pad position inside the helmet nor varying the size of the pad
7.2.2. Too Low
7.2.2.1. The ACH is too low if the helmet’s brim interferes with vision and/or eyewear 7.2.2.1.1. If helmet is deemed sitting too low, ensure chin strap is not over tightened
7.2.2.1.1.1. If after checking chin strap tightness the helmet still sits too low reassigning an individual to a smaller ACH shell size
7.2.2.1.1.1.1. In human factors testing, we will not allow for adjustment of the pad position inside the helmet nor varying the size of the pad
7.3. Evaluation of helmet looseness/tightness
7.3.1. Looseness
7.3.1.1. To check for looseness, have the individual shake their head rapidly from side to side to check for stability
7.3.1.2. If helmet shifts due to looseness, ensure chinstrap is adequately tightened
7.3.1.2.1. If chin strap is adequately tightened and shifting still occurs a size smaller ACH shell is