The wording and the drawing of rule IC 2.6.1 are not matching perfectly.

For that reason from now on the handling of the rule at FSG scrutineering will follow this principle: Inner diameter of the filler neck has to be equal or larger than 38 mm (as written and shown in rule/drawing). The filling cap diameter can be smaller (as long as large enough to fill fuel safely). It is the responsibility of the teams though to proof the 38mm diameter of the inside of the filler neck (behind cap). (Please see snapshot of rule).

The FSG team thanks the teams that helped bringing this concern up. We apologise for the additional effort this has created for the teams affected.