The Tu-154M and Tu-154M Lux are the most highly upgraded version, which first flew in 1982 and entered mass production in 1984. It uses more fuel-efficient Soloviev D-30KU-154 turbofans. Together with significant aerodynamic refinement, this led to much lower fuel consumption and therefore longer range, as well as lower operating costs. The aircraft has new double-slotted (instead of triple-slotted) flaps, with an extra 36-degree position (in addition to existing 15, 28 and 45-degree positions on older versions), which allows reduction of noise on approach. It also has a relocated auxiliary power unit and numerous other improvements. Manufacture continued through 2006, and there is still limited manufacturing as of January 2009.(photo link) Max. take-off weight increased first to 100,000 kg (220,462 lb), then to 102,000 kg (224,872 lb). Some aircraft are certified to 104,000 kg (229,281 lb). Tail numbers are 85616 (prototype), production aircraft from 85606 and on (except 85804, which is re-imported Tu-154B-2). About 320 were manufactured. Mass production ended in 2006. No new airframes have been built since the early 1990s, and production since then has involved assembling airplanes from components on hand.[10] This is the most widely used version in the former Soviet states.