What happened
On April 15, 2005, an Airbus A320-231, registration I-LINH, was cruising at FL300 near the Sorrento VOR when the flight crew experienced a loud impact followed by an extensive crack in the right cockpit windshield. Following the event, the crew proactively donned oxygen masks and initiated a rapid descent. After approximately two minutes, the crew determined that cabin pressurization remained stable, reduced the rate of descent, and diverted to Naples Capodichino Airport. During the approach, an "ANTI-ICE R WINDSHIELD" warning briefly appeared on the ECAM. The aircraft landed without further incident, and all 67 passengers and 6 crew members were unharmed.
The investigation
The ANSV investigated the cause of the structural failure, initially considering a birdstrike. However, ground inspections and chemical-biological analysis of the area near the damage ruled out any biological remains, making a birdstrike highly improbable at that altitude. The investigation then focused on the windshield structure, which was sent to the manufacturer for analysis.
Findings revealed that the damage was confined to the non-structural outer glass layer; the two inner structural layers responsible for aerodynamic and pressure loads remained intact. The analysis identified a "burn-out" defect in the electro-conductive heating layer located between the outer glass and the PVB resin interlayer. This defect caused localized overheating, which ultimately fractured the outer glass. The investigation traced the origin of this overheating to moisture infiltration, which had entered the assembly due to the erosion of the windshield seal, a result of normal service wear.
Findings
- The primary cause of the outer glass fracture was localized overheating of the heating element.
- This overheating was triggered by moisture infiltration into the heating layer.
- The moisture ingress was caused by the erosion of the windshield seal due to standard operational wear and tear.
- The component had accumulated approximately 21,600 flight hours since installation in 1998.