Aircraft Cabin Window Vent Hole

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 Aircraft Cabin Window Vent Hole 

 

Aircraft cabin window provide clear visibility from cabin to outside. It is required to have opening in aircraft structure to accommodate cabin window. Commercial aircraft normally fly at high altitude to get economy benefit but this pose safety issue for passenger due low ambient pressure. Thus, aircraft pressurized for passenger comfort and safety.

 

                                          Fig 01  Aircraft Cabin Window

Due difference in ambient and cabin pressure, pressurization load act inside of an aircraft structure.  To take pressurization load effectively structure must be strong and opening in the structure should be as small as possible and stiffened around the opening for structure stability. Aircraft window are smaller in size to ensure minimum pressurization load act on window. Window opening in the structure are oval shape to prevent stress concentration points.

Aircraft window comprises two window panes called main pane and inner pane. There is additional pane called scratch pane and it is for safety reason. The use of these two panes  increase window panes reliability. Main pane installed as outer window pane in window frame and it is relatively thick and has high fatigue strength. Inner pane installed as auxiliary pane in window frame and it is relatively thin and low fatigue resistance strength. The scratch pane covers the inner pane which prevent passenger touching  the inner or outer pane. Scratch pane is window retainer part.

The outer main pane away from cabin while the inner pane next to cabin. The panes installation in  window frame such that it creates space between the both panes. The both panes are held in window frame by seal arrangement and window frame secured to aircraft body structure.


 

Fig 02 Window Construction

The outer main pane takes up the cabin interior pressure under normal operating condition.  The inner auxiliary pane is not required to take up the inner cabin pressure under normal operating condition since cabin pressure effective in the space between inner and main panes.



Fig 03 Vent Hole on Inner Window Pane




Fig 04 Vent Hole 

The space between main and inner pane connected to the interior cabin through small diameter hole on inner pane called vent hole or breather hole.Vent hole equalize pressure between interior cabin and space between inner and outer pane and also ensure cabin pressure act on outer main pane under normal operating condition .During aircraft operation if outer main pane breaks, inner auxiliary pane take interior cabin pressure load. However, in such an emergency it is necessary to assure that the particular flight can continue to its destination without a total failure of the inner window pane.





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Comments

  1. UnknownJune 26, 2021 at 10:53 PM

    Beautifully explained in detail & simple to understand the concept.
    These small yet important technical concepts are really helpful.

    ReplyDelete

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