front of the Gromov Flight Research institute main gate. A Tu-144S, registration СССР-77106, is on display at Central Air Force Museum of Russia in Monino. Its maiden flight was on 4 March 1975, the final one on 29 February 1980. The aircraft was used to assess the effectiveness of the air-conditioning systems and to solve some problems on the fuel system. It can be considered the first production aircraft, being the first to be equipped for commercial use and delivered to Aeroflot. The first operational flight was on 26 December 1975 between Moscow and Alma-Ata carrying cargo and mail. This aircraft was the first SST to land on a dirty runway when she was retired to Monino. Another Tu-144, tail number СССР-77107, is on open display in Kazan and located at . The aircraft was constructed in 1975 and was a production model intended for passenger use. However, it was only used during test flights. On 29 March 1976 it made its last flight to Kazan. This aircraft was put on sale on eBay in 2017. TU-144S, tail number СССР-77108, is on display in the museum of Samara State Aerospace University (). It made its maiden flight on 12 December 1975, and its final flight on 27 August 1987. Development works on navigation system were made in this aircraft as well as flight-director approach. TU-144S, tail number СССР-77110, is on display at the Museum of Civil Aviation in Ulyanovsk. Maiden flight occurred on 14 February 1977, the final Flight on 1 June 1984. This aircraft was the second of the two aircraft used for regular passengers' flights on Moscow – Alma-Ata route. In 1977 it flew to Paris to take part in the XXXII Paris Air Show at Le Bourget Airport. This was the last appearance of a Tu-144 in West Europe. СССР-77110 was the last aircraft produced of the model Tu-144S, powered with Kuznetsov NK-144A engines. In the first half of 2008 the cabin was open for visits and between August and September was restored and painted in the original Aeroflot livery. The only Tu-144 on display outside the former Soviet Union, tail number СССР-77112, was acquired by the Auto & Technikmuseum Sinsheim in Germany, where it was shipped – not flown – in 2001 and where it now stands, in its original Aeroflot livery, on display next to an Air France Concorde. As of 2017, the Technikmuseum Sinsheim