Aircraft Windows

[jgm]

I have noticed that on commercial aircraft all the windows have what appears to be a tiny hole in, presumably, the inner skin at the bottom of the window. What is this for?

 

[SWComposites]

The innermost pane is just decorative and to protect the actual wiindow. The hole is presumably to allow for equalization of pressure on either side of the decorative pane, as it is not intended to carry loads.

 

[Wingtip46]

Also to provide a vent for condensation.

 

[Viking214]

The innermost window pane you see and touch is part of the interior shell and is non-structural. Unless the interior shell is removed/disassembled, the window is not accessible from inside the cabin.

The typical cabin window, behind that interior decorative pane, is made up of two plies. Some cabin windows have that tiny vent hole, for venting. Some windows do not have that vent hole.

As for loading, I have been involved in programs where both plies are considered structural. During cert testing in one program, with the outer ply failed, the inner layer withstood up to 40psi delta P.