Cessna 340 N5178J accident near Oklahoma City, Oklahoma

Probable cause

A failure of the windscreen for reasons that could not be determined based on available evidence.

NTSB analysis

While climbing through 17,000 ft mean sea level (msl) during a cross-country flight, the pilot completed a transition check and verified that the cabin pressure altitude was 8,000 ft and the pressure differential was within limits. As the airplane climbed through 18,000 ft msl, the right windscreen blew out. The pilot returned to the departure airport and landed the airplane without further incident.

Six pieces of acrylic material that comprised the complete outer circumference of the windscreen remained attached to the airframe. The section of windscreen that was blown out during flight was unaccounted for.

The fracture surfaces of the remnants were consistent with overstress separation. The pilot’s statement of events did not indicate a malfunction of the aircraft’s pressurization system. The origination point of the failure was not identified, and the reason for the windscreen failure could not be determined based on available evidence.

Text from the NTSB. Open the NTSB docket for CEN20LA378 for the full record.