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 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.
The investigation
The ANSV investigation initially considered a birdstrike, but ground inspections and chemical-biological testing of the area ruled this out, as no biological remains were found and a strike at such high altitude was highly improbable. The investigation focused on the structure of the multi-layer windshield. An examination conducted with the manufacturer revealed that the damage was limited to the non-structural outer glass layer; the two internal structural layers remained intact.
Technical 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 occurred because the windshield seal had eroded due to normal service wear. The component had accumulated approximately 21,600 flight hours since installation in 1998.
Findings
- The failure of the outer windshield layer was caused by localized overheating of the heating element.
- Moisture had infiltrated the windshield assembly due to the erosion of the windshield seal.
- The seal erosion was attributed to standard service wear and tear over the component's high-hour service life.