Jacky Eeckelaert has left the HRT team, where he was heading up the design work of its new 2012 challenger.
The Belgian was appointed to the role last October after Geoff Willis left during the summer, but HRT has opted not to give him a new contract after his existing one expired at the end of January.
"It is part of the restructuring of the team and the decision was taken some time ago," a spokesperson told AUTOSPORT.
Chief designer Jean-Claude Martens is now in charge of overseeing work on the new car, which it is hoped will make its debut at the first Barcelona test that kicks off on February 21.
Martens joined the team in the latter part of 2011.
Simon Jenkins, formerly head of production, has also left the team after his contract expired. His role has been taken by Dave Campbell.
The team will start testing tomorrow at Jerez with its 2011 car.