AIRCRAFT WINDOWS & WIND SCREEN CONSTRUCTION

WINDOWS & WIND SCREEN CONSTRUCTION

Windows: The windows for the passenger compartment of a large airplane must be designed and installed so there is no possibility that they will blow out when the compartment is pressurized. They must be able to withstand the continuous and cyclic pressurization loading without undergoing a progressive loss of strength.

An understanding of the installation of cabin windows for pressurized airliners can be obtained from a study of Figure 2.9, which shows the details for the installation of a window in the Boeing 720 airliner. One passenger window consists of outer, center, and inner panes. The inner pane is nonstructural and is mounted in the cabin sidewalk lining. (It is not shown in Figure 2.9). The outer and center panes are each capable of taking the full cabin pressurization load. Fail-safe structure is ensured by the center pane, which can take shock loading subsequent to outer pane failure. All three panes are of acrylic plastic with the structural panes being stretched and formed to improve resistance to crazing and increase the strength.

Another example of the window installation for a jet airliner is shown in Figure 2.10. This window installation is utilized in the Douglas DC-10 airplane.

1. The passenger compartment window shown in Figure 2.10 consists of two acrylic panes, a silicone seal, eight clips, and a window ring pan. The inner pane is approximately 0.20 in (5mm)  thick, and the outer pane is approximately 0.40 in (10mm) thick. The two acrylic panes are installed in the seal and are separated by an air space. The outer pane takes the pressure load that exists when the compartment is pressurized. If the outer pane should fail, the inner pane is designed with the strength to withstand the pressure load, thus providing a fail-safe performance. A small hole at the top of the inner pane and a slit in the bottom of the seal permit conditioned air to circulate between the panes to prevent condensation.

Figure 2.9: Installation of window for a pressurized aircraft

Figure 2.10: Installation of  passenger compartment window 

Windscreen/windshield: Windscreen or windshield is the fixed windows in the flight compartment. Normally there are two windshields: captain’s windshield and the first officer’s windshield. Besides, the flight compartment has other windows: sliding clearview windows, and aft fixed windows.

The two windshields are to be installed from outside the airplane on either side of the flight compartment centerline and are heated for anti-icing and defogging.

Removal and installation procedures for the left and right windshield panels are normally identical.  The windshield panels are removed from outside the flight compartment after all electrical terminal blocks have been disconnected.

When a windshield panel is changed because of an overheat condition, the electrical system must be functionally checked. Figure 2.11 illustrates removal of a windshield.

Figure 2.11: Removal of windshield panel