Passage: In February 1998 a new passenger terminal was opened in south area. On August 31, 2009, Infraero unveiled a BRL 525 million (US$ 276.6 million, EUR 193.8 million) investment plan to upgrade the International Airport focusing on the preparations for the 2014 FIFA World Cup, which was held in Brazil, Fortaleza being one of the venue cities. The investment was distributed in the renovation and enlargement of passenger terminal, apron, and parking with completion due in November 2013, however after abandoned. Just a removable Tent was made.Through a partnership between Infraero, federal government and state government, the 35,000 m² passenger terminal was built in the southern area, inaugurated in February 1998, by Governor Tasso Jereissati, whose capacity was 3.8 million passengers per year, 14 aircraft parking positions and with automation systems, being classified as International in 1997 (Portaria 393 GM5, of June 9, 1997). It was auctioned on March 16, 2017 to the consortium Fraport AG of Frankfurt, Germany for R$ 425 million for use for 30 years. Among the established in the contract is the reform of the current terminal and termination of the attached work, abandoned by Infraero, as well as increase of the only runway. From June 2017 to 2018 both companies run the entire airport, as of 2018, it manages the airport entirely in its operations. The contract signed on July 28, 2017 says to renew and complete the investments of Infraero for the passenger terminal and the lengthening of the single runway.

Question: When was a legally binding document signed?
July 28, 2017