A chip is considered a small scratch.
A foggy appearance located on the surface of the transparent material.
Speck, air bubble, or other minor imperfection imbedded in the transparent
material.
An almost nonexistent shallow depression on the surface possessing practically no
depth. Discernible only due to a noticeable rim or roughened surface caused by
mold surface defects transferred to the surface during the forming operation.
Visible evidence of a physical break of the bond between the plastic interlayer and
either glass ply. Delamination may be caused by laminating stresses, preload on
installation, or excessive heat.
EFFECTIVITY:
040-999
56-00-00Feb 1/98
PIPER AIRCRAFT
PA-42-720(AdvancedTrainer)
MAINTENANCEMANUAL
(b)
CRITICAL AREA INSPECTION -GLASS WINDSHIELDS. A critical area is the area of the laminated glass windshields used for taxiing, takeoff, climb, cruise, and landing.
(1)
Cracks could occur in either the inner, outer, or both panes. Cracking in either pane is critical and cause for immediate replacement.
(2)
Crazing.
(a)
Crazing in the windshields is critical.
(b)
Determine depth of craze using a calibrated depth gauge or scale (see Figure 601).
(c)
A craze of 0.062 inch (1.575 mm) depth is cause for immediate replacement. A craze of
0.031 inch (0.787 mm) depth is cause for replacement at the earliest opportunity.
(d)
Crazing in any portion of the windshields requires replacement.
(3)
Blemishes.
(a)
Blemishes in windshields form in the vinyl plastic interlayer bonding the two glass panes together.
(b)
Blemishes in the critical or semi-critical portion of the windshields are not acceptable unless 0.062 inch (1.575 mm) or smaller in circumference, including distorted area.
(c)
No more than two blemishes, at least 12 inches (30.48 cm) apart are acceptable in the windshields.
(d)
No more than two blemishes within a two inch (5.08 cm) area along the upper portion of the windshields are acceptable.
(4)
Haze or foggy appearance on the glass is not acceptable if the amount of haze/fog causes an obstruction of vision in the area used for operation of the aircraft.
(5)
Scratches.
(a)
A scratch, no longer than 0.062 inch (1.575 mm) long and no deeper that 0.015 inch (0.381 mm) is acceptable.
(b)
Heavy scratches on either glass ply are cause for immediate windshield replacement.
(c)
Hairline scratches may be waxed and buffed out.
(6)
Delamination.
(a)
Cloudy or milky appearance in the delamination indicates moisture or solvent penetration. Windshields with this condition should be replaced at the earliest opportunity.
(b)
Delaminated areas characterized by irregular or jagged boundaries indicate uneven separation of the vinyl and glass. This condition may cause the vinyl to pull chips from the inner glass surface, resulting in failure of the glass ply. Conduct periodic inspections to determine if the damage is progressive or if chipping of the inner glass surface is present.
(7)
Mark-Off of such low intensity that vision quality is not impaired and that is not visible when looking through the windshield is acceptable.
(8)
Distortion. Slight horizontal distortion is acceptable, if: there are no more than two lines; they do not occupy more than 25 percent of the windshield area, and; they are separated by a minimum of six inches (15.24 cm).
(c)
SEMI-CRITICAL AREA INSPECTION -GLASS WINDSHIELD, COCKPIT ACRYLIC WINDOWS. Semi-critical areas are the perimeter of the glass windshield and areas of cockpit acrylic windows used for general flight vision.
(1)
Mark-Off of such low intensity that vision quality is not impaired and that is not visible when looking through the windshield is acceptable.
EFFECTIVITY: PAGE 2 040-999
Feb1/98 56-00-00
PIPER AIRCRAFT
PA-42-720(Advanced Trainer)
MAINTENANCEMANUAL
(2)
Distortion.
(a)
A moderate amount of distortion is acceptable along the lower portion of the windshield if no more than 1.5 inches (3.81 cm) above the windshield retrainer strip.
(b)
Distortion may not be so severe that it restricts vision or diverts runway lines or section lines more than 45 °.
(c)
Slight horizontal distortion is acceptable, if: there are no more than two lines; they do not occupy more than 25 percent of the windshield area, and; they are separated by a minimum of six inches (15.24 cm).
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