What happened
Approximately 15 minutes after departure, while the aircraft was climbing through an altitude of 12,000 to 12,500 feet, a rapid decompression occurred. At the time of the event, the cabin differential pressure was 4.3 psi. The separation of the flight compartment side 'D' window caused the loss of pressure. Following the incident, the pilot diverted the aircraft to the destination airport and completed the landing without further incident. No injuries were reported.
The investigation
An examination of the failed window following the incident revealed preexisting cracks. These cracks originated on the external surface of the window at the transition radius located between the center portion of the window and the window flange. The component involved in the failure was the latest design and had accumulated 4,008 hours of flight time since its last replacement.
A review of the established inspection protocols for this window type was also conducted. The investigation found that while inspections are scheduled to occur every 600 hours, the current requirements do not necessitate the removal of the metal retaining ring during the inspection process.