The suit, which seeks unspecified monetary damages, also alleges that the helicopter was designed and built by Airbus Helicopters, a unit of Airbus, with flaws to its tail rotor system which malfunctioned and made the aircraft "uncontrollable in the event of a failure, especially at low speeds, hover and/or liftoff."
In the context of the input sentence, determine the relationship between 'Airbus' and 'aircraft'.
Options: developer, owned by, product/material produced, chief executive officer