(d)
Chips:
1) The Spall (shell type) chips have circular or curved edges. They have many small hairlines or ridges that follow the outline of the outer edge. They get smaller toward the center or deepest point of chip, similar to a clamshell.
2) Vee shaped chips have a sharp narrow V shape and look like they go to the interior of the plastic.
(e) In-plane cracking: A smooth surfaced fissure, or series of fissures, along the pane surfaces. In-plane cracking can occur in stretched acrylic. It starts at the edges of the pane or at deep penetrations of the window. It is usually found by the reflection of light from the smooth surfaces of the fissure.
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B. Standard Tools and Equipment
(1) Optical Micrometer - Model 966A1
Monocle industries
P.O. Box 2426
Coppell, Tx. U.S.A. 75019
Tel (214) 393-9920
Fax (214) 393-9926
C. References
(1)
AMM 12-16-04/301, Passenger Windows
(2)
AMM 56-21-01/401, Passenger Windows
(3)
AMM 56-21-01/801, Passenger Windows
(4)
OHM 56-21-41
D. Access
(1) Location Zones 211 Passenger Cabin Nose to First Door, Left 212 Passenger Cabin Nose to First Door, Right 223 Fwd Upper Deck Passenger Cabin, Left 224 Fwd Upper Deck Passenger Cabin, Right 225 Aft Upper Deck Passenger Cabin, Left 226 Aft Upper Deck Passenger Cabin, Right 231 Passenger Cabin First to Second Door, Left 232 Passenger Cabin First to Second Door, Right 241 Passenger Cabin Second to Third Door, Left 242 Passenger Cabin Second to Third Door, Right 251 Passenger Cabin Third to Fourth Door, Left 252 Passenger Cabin Third to Fourth Door, Right 261 Passenger Cabin Fourth Door to Sta 2040, Left 262 Passenger Cabin Fourth Door to Sta 2040, Right 271 Passenger Cabin Sta 2040 to Sta 2360, Left 272 Passenger Cabin Sta 2040 to Sta 2360, Right
E. Procedure
S 216-002
(1) Examine the windowpanes for cracks and crazing.
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CAUTION:_______ DO NOT PRESSURIZE THE AIRPLANE WITH A CRACKED OR CRAZED
MIDDLE PANE. PRESSURIZATION OF THE FUSELAGE WITH THE
MIDDLE PANE CRACKED OR CRAZED IS DANGEROUS BECAUSE THE
FAIL-SAFE PROPERTY IS REMOVED.
(a) Replace the middle panes that have cracks or are crazed (AMM 56-21-01/401).
NOTE: Middle pane cracks that start from the vent hole and are
____
0.062 inch or less in length do not need to be replaced.
You can repair the middle pane if the minimum thickness after the repair is 0.180 inch (OHM 56-21-41).
(b) Replace the outer pane if the depth of any single crack or craze is 0.05 inch or larger (AMM 56-21-01/401).
NOTE: An accurate depth of the crack is measured with an
____ optical micrometer. To get the correct dimension, multiply the acrylic plastic index of refraction (1.49) by the micrometer value. All accurate procedures to measure the crack depth are permitted.
(c) Replace the outer pane if the pane thickness after repair will be less than 0.280 inch (AMM 56-21-01/401).
NOTE: You can repair the outer pane if the minimum thickness
____ after the repair procedure is 0.280 inch. Cracks start in the outer pane from scratches and/or crazing (Fig. 601).
(d) Replace the outer pane if the depth of a crack or craze is more than 0.03 inch on the bevel edge (AMM 56-21-01/401).
NOTE: A 0.03 inch maximum depth of a crack or a craze on the
____ bevel edge is permitted. A minimum 0.170 inch thickness of uncracked and uncrazed material must exist at all points, 0.30 inches or more from the outer edge. With in-plane edge cracking, 0.170 inch applies to the material between the in-plane cracks and the bottom of the bevel edge cracks and/or crazes (Fig. 602).
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