The FIA has moved to stamp out a Gurney flap trick that could have handed Formula 1 teams a set-up advantage in races, Autosport can reveal.
Paddock speculation emerged after the season-opening Australian Grand Prix that some outfits had found a clever way to better balance the compromise between qualifying and race trim with F1's new aero rules for 2019.
It was suggested some competitors were playing around with moving the location of their front wing Gurney flaps - the small vertical flip that is attached to the trailing edge - under parc ferme conditions between qualifying and the race.
This could help teams either by allowing them to run with more downforce in qualifying, or by helping with aerodynamic balance in the race for improved tyre management.
Although teams are not allowed to change the specification of car parts between Saturday and Sunday, the argument was that regulations did not specifically outlaw moving components around that had been run in qualifying.
Article 34.2 n) of Formula 1's sporting regulations states: "The aerodynamic set-up of the front wing may be adjusted using the existing parts. No parts may be added, removed or replaced."
If a team wanted to remove the Gurney flap it had used in qualifying and relocate it somewhere else on the car, it would in theory not breach the wording of this rule.
However, with the FIA aware of teams' concerns about the trick, it looked into the matter ahead of this weekend's Bahrain GP.
Although it is understood the FIA does not believe any teams moved their Gurney flaps in Australia to exploit the rules, it has moved to outlaw the activity with a pre-emptive strike.
In Bahrain, teams were issued with a technical directive making it clear that the removal of parts like Gurney flaps and relocation to another area of the car would be viewed as a breach of F1's parc ferme rules.
Any team making such a change would be deemed to be running with a new specification of front wing so would have to start the race from the pitlane.
Not all teams have Gurney flaps on their front wing, but Williams, Alfa Romeo, Red Bull and Renault have all run them so far this season.
How a Gurney flap change could help
Gurney flaps have been a part of Formula 1 for decades - invented by American driver Dan Gurney for his own racing operations.
The flap is simply a small vertical piece attached to the trailing edge of a wing. Although small, the Gurney flap changes the airflow characteristics around the wing quite dramatically.
First, it produces a little rolling vortex in the corner where it attaches to the wing, but this helps to develop a greater pressure difference between the top and bottom surfaces - improving the overall downforce.
Behind the flap, two vortices begin to rotate behind to draw the separated airflow back together. In essence, the flap is able to produce a similar effect to position the wing at a higher angle of attack, but with a slightly reduced drag penalty.
Adding these simply allows the car to reap the benefits of more front-end downforce and hence makes it more responsive, meaning a driver can angle the car more easily on an all-or-nothing qualifying lap.
By taking the Gurney flaps off, this suggests an aerodynamic imbalance in race trim, and dialling out some of the front end downforce can assist with this.
Alternatively, it may be that the team experiences greater tyre wear with the addition of the flap, and would be trying to preserve the fronts by not working them too hard with the added downforce.