What happened
On 26 October 2006, a Swedish Coastguard CASA C-212 aircraft, registration SE-IVF, was conducting a routine maritime surveillance mission. After departing from Ronneby airport, the crew received a request to perform a fly-by over the Falsterbo canal base. The crew adjusted their flight plan to include a demonstration of the aircraft's capabilities.
While performing the demonstration, the aircraft flew over the canal and executed several wing-tipping maneuvers. During one of these maneuvers, a loud bang was heard, and the left wing suddenly separated from the fuselage. The aircraft rolled onto its back and plunged into the northern basin of the Falsterbo canal. The impact destroyed the aircraft, and all four people on board were killed.
The investigation
The Swedish Accident Investigation Authority (SHK) conducted a technical examination of the wreckage and the aircraft's structural integrity. Investigators focused on the wing attachment points and the wing lower skin. Metallurgical analysis revealed an 84 cm long fatigue fracture in the lower skin of the left wing, specifically where the wing attaches to the fuselage.
Further testing and examinations of the right wing showed that a similar, though less developed, fatigue crack was present in the same location. Investigators also performed flight tests and fatigue testing on samples to understand the crack initiation process and the impact of operational loads on the structure.