As first reported earlier this month, the FIA has been taking a close look at flexible wings over the first half of this season as it believes teams have been pushing the boundaries in terms of what is allowed.

It is understood that several teams, including Aston Martin, were advised to make changes to their front wing designs around the time of the Azerbaijan Grand Prix in a bid to ensure that they did not fall foul of any rule breaches.

But as part of a ramped up effort to stop any attempt at getting around the regulations, the FIA has now issued a formal technical directive outlining what it believes are unacceptable designs with regards to flexible bodywork.

In TD018, a copy of which has been seen by Motorsport.com and was sent to teams ahead of the Dutch GP weekend, the FIA states that it believes outfits are exploiting “regions of purposely design localised compliance” plus “relative motion between adjacent components” to deliver a significant boost to aerodynamic performance.

It states that any design that operates like this is in breach of Article 3.2.2 of F1’s Technical Regulations, which states that all components that influence a car’s aerodynamic performance must be “rigidly secured and immobile with respect to their frame of reference defined in Article 3.3.

Furthermore, these components must produce a uniform, solid, hard, continuous, impervious surface under all circumstances.”

The FIA has been prompted into action because it believes that teams are exploiting sophisticated systems that rotate and flex front and rear wing elements in ways that cannot be detected through the regular load tests.

It has made it clear that any “assembly designs that exploit localised compliance or degrees of freedom are not permitted.”

The FIA has duly outlined four key design elements that it considers to be in breach of the technical rules, but suggests there may be other ideas at play that could be illegal as well.

They are:

1. Wing elements that can translate vertically, longitudinally or laterally relative to the bodywork that they are fixed to.

2. Wing elements that can rotate relative to the bodywork that they are fixed to, such as rotating around one fixing.

3. Designs that utilise elastomeric fillets, compliant sections of wing profile or thin flexible laminate at a junction that can either distort, deflect out of plane or twist to permit localised deflection relative to the bodywork the component is attached to.

4. Designs that utilise ‘soft’ trailing edges to wing elements to prevent ‘localised cracking’ as the result of component assembly deflection.

The only exemptions that will be allowed are in the area of floor assembly, bib bodywork and the opening of a small lateral gap to help the sealing of front wing flaps.

Whereas in the past, teams’ flexi wing antics were often responded to by the FIA increasing the load tests that take place in the garage, the realisation that teams may be using clever trickery to make the wings flex in ways that cannot be checked when the car is stationary has prompted a change of approach.

From now on, teams must submit the assembly drawings and cross sections that show the fixation of the front wing elements to the nose, as well as the rear wing elements to the endplates, rear impact structure and pylons.

Furthermore, teams have to supply similar images that show the fixation of the rear wing pylons to the rear impact structure.

These designs will allow the FIA to better understand how the wing components have been designed and if any team has created its parts in a way to flex and deliver an aerodynamic advantage.

Because of the potential work needed by teams to ensure full compliance with the regulations, the FIA has delayed the adoption of its new stance until the Singapore Grand Prix next month - which means competitors can continue with their current designs through to the end of this weekend's Monza race.

Teams have been asked to submit all the necessary drawings that show their wing designs by 8 September.