8
Chapter 2: Helmet Preparation and Operation
2-2 1 Determining Helmet Size
To determine helmet size, you measure the aircrew member's
head length
and
head width
.
After you make these measurements, you then compare the measurements to established size
data and
select the helmet size
accordingly.
Tools/Equipment/Materials Needed
• Caliper
); used to measure head length and width; may be locally manufactured
from sheet aluminum, plastic, or cardboard
• Ruler
calibrated in inches to tenths (or metric); used to obtain the dimensions of the caliper
measurements
(Continued on next page)
Proper fitting of the helmet is imperative for the safety of the aircrew member. An
improperly fitted helmet can become unstable (failing to provide bump protection),
or it can be lost during a high-speed ejection (causing injury to the aircrew member).
Ensure that the helmet is properly fitted to the aircrew member.
30°
4
1
/
16
inches (104 mm)
1
/
4
inch (6 mm) R
10 inches (254 mm)
1
/
2
inch (13 mm)
1
1
/
8
inches
(29 mm) R
1
15
/
16
inches
(49 mm)
3
7
/
8
inches (98 mm)
Figure 2-1. Caliper
