What happened
On April 15, 2005, while cruising at FL300 near the Sorrento VOR, the crew of an Airbus A320-231, registration I-LINH, 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 confirmed that cabin pressurization remained stable, reduced the rate of descent, and diverted to Naples Capodichina Airport. During the diversion, an "ANTI-ICE R WINDSHIELD" indication briefly appeared on the ECAM. The aircraft landed safely without further incident.
The investigation
The ANSV investigation initially considered a birdstrike, but ground inspections and chemical-biological analysis of the area ruled this out, as no biological remains were found and a strike at such high altitude was deemed highly improbable. The investigation focused on the structural integrity of the multi-layer windshield.
An examination conducted at the manufacturer's facility 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 investigation 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, leading to the fracture. The root cause of the heating element failure was traced 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 its installation in 1998.
Findings
- The crack in the outer windshield layer was caused by localized overheating.
- This overheating was triggered by a defect in the heating element.
- Moisture entered the heating element assembly due to the erosion of the windshield seal from standard service wear.