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|  MIL-W-81752A(AS)
3.8.6.7 Distortion
3.8.6.7.1 Fighter/attack type aircraft - The maximum gridline
slope for the windshield shall be 1:15 when the grid is photographed
through the windshield in the installed position.
3.8.6.7.2 Other aircraft - The requirements of 3.8.6.7.1 apply.
In addition, normal roll-off distortion of 1:1 in Zone III shall not
be cause for rejection.
3.8.6.8 Magnification - The maximum magnification shall be not
greater than 8 percent and a minus value indicating a reduction in
size shall be less than -8 percent.
3.8.6.9 Birefringency - The rainbow associated with internal
stresses and variation of individual ply thickness and internal stress
shall not be permitted when the windshield is photographed and
visually inspected. A color photograph shall be taken from the left
and right eye position at zero azimuth.
3.8.6.10 Visual performance - The windshield shall be inspected
visually. There shall be no immediate apparent bending, blurring,
divergency, convergency, or broken gridlines. Defects less than 0.035
inches in diameter shall be acceptable if not located or grouped in a
manner to cause vision impairment. Any optical defect, regardless of
size, which causes vision impairment shall be cause for rejection.
Defects in Zone III are permitted if structural integrity of the
The entire windshield, including Zone
windshield is not affected.
III, shall be free of bull's eye type distortion (See 6.3).
3.8.6.11 Scratches - Scratches shall be evaluated using ASTM
F-428 Standards. There shall be no scratches more severe than
F-428-3 in Zone I. There shall be no scratches more severe than
F-428-4 in Zone II. There shall be no scratches more severe than
Scratches that are equal to, or less severe
F-428-6 in Zone III.
than, the limits defined are acceptable, provided they are not of a
length or density that impairs vision.
3.8.6.12 Color - When polycarbonate material is used in
windshield construction, the yellowness of the core ply mill run prior
to fusion bonding shall be determined. The yellowness index (YI) for
a mill run ply of 0.25 inch thick polycarbonate shall be not greater
than 8.5.
3.8.7 Cockpit reflections - Windshield and canopy configurations
which produce objectionable patterns of reflections of cockpit and
external lights shall be coordinated with locations of internal light
sources, light baffles, and orientation of reflective surfaces for an
optimum configuration. Proposed cockpit enclosure configuration.
shall be verified by a lighting mockup. Point secure and distributed
illumination effects shall be demonstrated.
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