What is the fine-grained topic of the following text: Sikorsky, February 13, 2012 - DALLAS, Texas - Sikorsky Aircraft today announced that Bond Aviation Group, the British helicopter operator and subsidiary company of the World Helicopters Group, has signed a contract to buy 16 S-92® helicopters. Only return the topic.
Bond Aviation Group's purchase of 16 S-92 helicopters from Sikorsky Aircraft