Mercedes brought a new front wing to China, but FIA was not happy with the design of new endplates so the world champions had to modify their new wing before the first free practice session.
The new front wing has a different profile of the main plane at the point where it is connected to the endplate, but also new endplate design with curved rear vertical edge (turquoise) and shorter upper horizontal edge to allow more air to move to the outside of the front wheels.
But the problem is that the uppermost element of the front wing (orange) is seen from the side perspective, which is forbidden by the technical regulations for 2019.
Article 3.3.5 of the 2019 F1 Sporting Regulations requires, among other things, that 95% of the front wing side projection is covered by the endplate, leaving the teams room for small cracks at the end of the endplates.
But Mercedes tried a little too much and the FIA was not happy with their interpretation, as they believe that more than 5% of the front wing side projection is visible.
A similar thing had previously been tried by Red Bull and Williams who also had to modify their front wing.
After the FIA informed them that the new front wing did not meet the rules, Mercedes lowered the surface of the front wing’s uppermost element near the endplate so it would not be visible from the side perspective.
In that configuration wing made its debut in both free practice sessions for 1000th Formula One race in China, as pictured bellow.