4-37. MASK TO HELMET ADJUSTMENT.
Use the following procedures to accomplish mask to helmet adjustment.
a. Don helmet and adjust nape strap
to obtain snug fit.
b. Attach mask assembly to helmet by
inserting oxygen mask fitting into
the second locking position of the
c. Greater adjustment can be
achieved as follows:
Remove four tackings on the
retainer strap using a razor or
Adjust buckles to the desired
Retack around the lower bar of
the four buckles with two turns of
double waxed thread, specifica-
tion VT-276, Type IV B, tucked
8/4, or equal.
Tie thread ends with a surgical
knot and secure with a locking
d. Adjust straps to obtain a snug, com-
fortable fit of mask to face without
When leakage occurs between face and
mask, verify mask part number with fig-
ure 3-2. When proper mask is being
used and leakage occurs, proceed to