P flyer\'s helmet.

Pages 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 - 13 - 14 - 15 - 16 - 17 - 18

MIL-DTL-87174A(USAF)

3.5.1 Buckles and thread. Buckles shall be a 2�bar design, 0.75 inches wide, and constructed of

brass. See Drawing 4�1�54. The buckles shall have a black chemical finish applied in accordance

with established commercial practices (see 6.8). The thread shall be nylon, size 1, black, general

purpose, twisted multiple cord (ply) construction, bonded or unbonded with a soft finish. Each of

the individual yarns shall be twisted initially with not less than 6.0 turns per inch (tpi), and in the

opposite direction to the final twist. The final plied twist shall be not less than 6.0 tpi. The thread

size parameters shall be in accordance with table I.

TABLE I. Thread Sizes.

Final

Elongation

Nominal

Breaking

Tex

Length per

Thread

force

Twist

percent

Size

Ply

(t.p.i.)

maximum

Number

pound (yards)

minimum

(g/km)

pounds

6.0

68 � 76

5,801 - 8,700

2 or 3

7.0

8,701 - 13,000

3.5.2 Visors.

3.5.2.1 Visor lens coating. The visor lens shall be polycarbonate with optical characteristics in

accordance with MIL�V�43511. The visor lens shall be coated on the front and rear surfaces with

an abrasion resistant coating in accordance with MIL�C�83409.

3.5.2.2 Visor assembly, lightweight (Clear - MBU�12/P Trim). The lightweight visor assembly

(Clear - MBU 12/P Trim) shall be in accordance with Drawing 81D5189�3.

3.5.2.3 Visor assembly, lightweight (Neutral Gray - MBU�12/P Trim). The lightweight visor

assembly (Neutral Gray � MBU�12/P Trim) shall be in accordance with Drawing 81D5189�4.

3.5.3 Headset assembly. The H�154A/A1C headset assembly shall be in accordance with Air

Force Drawing 7136036 except that the color of the earcup, earseal, and earcup inserts shall be

black.

3.5.4 Absorbent liner. The absorbent liner shall be in accordance with Drawing 70360. The

fabric used in the construction of the absorbent liner shall be preshrunk prior to cutting and

stitching, shall be knitted simplex, Type I, and shall be gray. The thread used in the construction of

the absorbent liner shall be size 2, nylon, general purpose twisted multiple cord (ply) construction,

unbonded with a soft finish. Each of the individual yarns shall be twisted initially with not less than

7.0 t.p.i., and in the opposite direction to the final twist. The final plied twist shall be not less than

7.0 t.p.i. The thread size parameters shall be in accordance with table I.

3.5.5 Retainer jack. The retainer jack shall be in accordance with Drawing 60B4278.

3.5.6 Pad set, fittings, earcup. The pad set, fittings, and earcup shall be in accordance with

Drawing 64A2217�4.