Bob,

 

My window cracked at about 250 hours and I had a fast build door as well. My kit is 506 and was purchased in 2000. I fly consistently at FL250 and a few times at FL280. When I repaired it I put a lot more carbon over the stiffener section. The crack was in the upper rear corner and went around the corner right against the carbon outer shell. It was very difficult to see as was yours and I noticed it when cleaning one day. Mine cracked at FL250 and sounded like a baseball hit the door somewhere.

 

One possible theory is could be overpressure on the door seal in addition to the cabin pressure. I noticed when testing the pressurization  on the ground that the door is pushed outward by the door seal.

 

Another friend of mine blew this window out of the plane at FL210 near Bend, OR. His was not a fast build door. Luckily his wife was not in the plane with him. She would not enjoy flying quite as much any more.

 

I wonder if there are others out there that have had this problem.

 

Gary Garratt San Martin, CA 408 888 1500