All 154 Rosebank employees will remain with the company that has been renamed Rosebank Engineering Australia Ruag.
The contract for an undisclosed sum was signed earlier this month, a statement from Ruag said.
Rosebank has headquarters in the Melbourne suburb of Bayswater and employs up to 200 people. Apart from aviation repairs and servicing, it offers precision machining of flight controls, landing gear and airframe parts and other high-technology mechanical and hydraulic engineering services.
Ruag, with headquarters in Bern, Switzerland, has been supporting customers in the Asia-Pacific region from its facilities in Malaysia and Europe.
"The (Rosebank) transaction means that Ruag can now offer comprehensive life-cycle support out of Australia," said Philipp Berner, chief executive of Ruag's aviation division.
"Internationally, Rosebank will be represented by Ruag. The parties have agreed not to disclose the price of the shares sold."
Ruag's Asian clients include Hindustan Aeronautics in India, for whom it's performed engine and propeller upgrades for the military's fixed-wing turboprop Dornier Do228 aircraft.
Last year the Bangladeshi navy bought two new upgraded Dornier 228NG aircraft -- an updated version of the Dornier-built 228-212 -- from Ruag Aviation for maritime patrol and rescue missions.
The Bangladeshi deal includes a comprehensive pilot and aircraft maintenance training plan for naval ground crew.
Ruag said the order is the first by the Bangladesh navy for a fixed wing maritime patrol aircraft and delivery is expected for early summer 2013.
Ruag also is in the shortlist for running Australia's munitions factories. Its Ammotec division has teamed with German suppliers Rheinmetall Waffe Munition and Nitrochemie in a bid for the Domestic Munitions Manufacturing Arrangements project.
Under the DMMA contract, the winner will run the two non-guided missile armaments production centers of Mulwala, a government owned establishment, and Benalla, built in 1996 and owned by Thales Australia.
Both centers have been run by Thales since the 1990s.
The DMMA contract winner is expected to take over in the last half of 2015. The winner also will work with the Australian Department of Defense on general munitions procurement strategies.
Last month Ruag appointed Andreas Fitze as its group chief information officer to replace Oliver Meyer, who becomes head of simulation and training in Ruag's defense division.
Fitze, 44, holds an electrical engineering degree and an MBA from the University of St. Gallen in Switzerland. He leaves his job as head of IT governance, strategy and security at PostFinance in Bern in the spring, Ruag said.