In fact, there have been remarkably few times in F1’s history that planks have been found to have worn down too much – with the most famous still being Michael Schumacher’s disqualification from the 1994 Belgian Grand Prix.
This makes it even more intriguing that, in an area of the car that teams are very mindful of there being no room for error, two of the top squads tripped up on the same race weekend.
The explanations as to how the rule breaches happened seem to be clear, which is why both teams had to simply accept their fate with the stewards once the planks were found to be worn away too much.
As Mercedes boss Toto Wolff said: “There's no wiggle room in the rules. We need to take it on the chin, do the learning, and come back stronger.”
The tolerance between success and failure over plank legality is tiny, given there can be no more than 1mm of wear between a freshly fitted plank and one that’s gone through all the rigours of a race.
To check compliance with the rules, the FIA is able to measure wear on the plank at four 50mm diameter holes drilled into the surface at specific locations designated within the technical regulations.
In the instance of Leclerc and Hamilton, it was the rearmost hole that failed the test. This hole must be positioned on the car’s centreline between 825mm and 1025mm ahead of the rear axle line.
As can be seen from the main image, this in itself offers some variability as to how wear can occur on different cars, given that there is not a specific point for the drill hole, unlike the three holes at the front of the plank.
The drill holes made in the plank (which is no longer made of wood, rather it is a composite material) are surrounded by flush mounted titanium skids.
These offer further protection from wear and are also tightly regulated in their design. This is an area that the FIA has been closely monitoring with this new generation of cars, and it has served several technical directives as a response to inconsistencies in their design already.
Source: Autosport