Offshore Aircraft Loss Due to Vertical Fin Separation (N213AL)

Incident Overview and Search Operations An aircraft departed from an offshore rig, but the pilot did not complete the required 15-minute radio check after departure. As a result, a radio and air search was initiated. Approximately two hours after the missed check, debris was located floating about three miles from the departure point. ## Technical Findings The recovered debris indicated that the aircraft had experienced an in-flight separation of the vertical fin, followed by mast bumping. Metallurgical examination of the vertical fin attachment fittings showed that they had separated due to fatigue induced by corrosion and corrosion pitting. ## Maintenance and Fracture Evidence The examination also revealed that the operator had unsuccessfully attempted to combat the corrosion during a refurbishment of the airframe. All of the fatigue fractures appeared old, and one fracture contained paint, indicating that the damage had been present for a significant period before the accident.