First flying on December 23, 2013, the Z-20 shares similarities and components, like the passenger cabin, with the ubiquitous American S-70/UH-60 Blackhawk helicopter (China currently owns about 22 S-70s). However, the Z-20 has five blade (vs. the S-70's four blade) main rotor, Chinese engines and gearbox, and a smaller tail. The Z-20 weighs about ten tons and can either carry four tons of external cargo or twelve infantry. Once in service, the Z-20 would replace China's foreign designed Z-9 and Mi-171 helicopters, providing various military units such as mountain troops and submarine hunters with a capable air platform. It would also operate as a search and rescue, transport and anti-submarine warfare helicopter for Chinese warships too small to carry the Z-18.