Gentex HGU-55/P, Operation And Maintenance Instructions With Illustrated Parts Breakdown

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11
Chapter 2: Helmet Preparation and Operation
5. Have the pilot fasten and adjust the
chin strap as follows ( Figure 2-6 ):
a. Snap the chin strap.
b. Adjust the end of the chin strap
so that the nape pad fits snugly
against the back of the head.
c. Center the chin pad under the
chin. Attach the end of the chin
strap to the chin pad.
6. Referring to Figure 2-7 , check
the height from the edge of the
helmet to the aircrew member's
eye pupils. This height should be
approximately 1½ inch ±¼ inch
(38 mm ±6 mm) for maximum field
of view.
If the height is correct, go to Step
11 (next page).
If the height is not correct, perform
Step 7.
7. Attempt to adjust the height by
rotating the helmet forward or
rearward as applicable. Readjust
the chin strap. Perform Step 8.
8. Check the height as in Step 6.
If the height is correct, go to Step
11 (next page).
If the height is not correct, perform
Steps 9 and 10.
9. Re-fit the TPL, SCL, or XLiner (Paragraph 2-2.2). Then perform Step 10.
10. Check the height of the helmet as in Step 6.
If the height is correct, go to Step 11 (next page).
If the height is not correct, obtain a helmet of a different size and return to Step 1.
(Continued on next page)
Nape pad
(inside helmet)
LOWER FRONT VIEW OF HELMET
Snap
Buckle
End of chin strap
Chin pad
Figure 2-6. Fastening Chin Strap
Figure 2-7. Measuring Helmet Height