Latest photo of their Z-20 copyhawk in Tibet
This might be a real reverse-engineering project. Unlike the Flanker which took less than a decade for an exact version to be made, the Z-20 took close to 30 years to clone from Blackhawks imported during the 1980s and is not an exact copy owing to lack of OEM support.
Time comparison of a TOT with OEM support versus RE without:J-11
initial access — 1998 (Su-27SK license)
first flight of copy — 2004 (J-11B with AL-31)
induction — 2007 (J-11B in PLAAF with WS-10 engine)Z-20
initial access — 1984 (import of S-70C-2 Blackhawk)
first flight of copy — 2013 (Z-20 with P&W PTC6)
induction — 2017? PLA eval unit? at best LSP not mass production
RE takes decades longer than ToT and the copies are not exact to make most of domestic parts. TOT like the J-11 are exact clones of the product sold and development of variants is lightning fast with help from the OEM (provided you negotiated a proper license.) In the J-11 case, this included a re-engine and a carrier variant, all done concurrently inside a decade.