Hawker Beechcraft Corp. C90 N2057C incident near Evansville, Indiana

Probable cause

The peel chip-type failure of the co-pilot's window during initial climb.

NTSB analysis

During the initial climb after takeoff, the inner ply of the co-pilot’s windshield in the pressurized turboprop airplane shattered. The remainder of the windshield was not shattered. The pilot diverted and landed without further incident. Microscopic examination of the windshield's crack initiation area revealed an expanding triangular or v-shaped area emanating from a single point, consistent with a peel chip. The peel chip-type fracture of the inner ply of glass has historically been an issue on the King Air windshield and the window manufacturer made a product improvement to it. The windshield improvement incorporated a urethane layer between the vinyl interlayer and the inner glass ply that relieves stresses on the inner glass ply and prevents peel chip fractures. This airplane did not have the improved windshield. To date, there has not been a peel chip type fracture with the improvement in place.

Text from the NTSB. Open the NTSB docket for CEN11IA180 for the full record.