Counterbore protection dish for mounting without interference

An aircraft mechanical part comprising a protected counterbore, said protected counterbore comprising a counterbore comprising a cylindrical wall of a predetermined diameter and a bottom wall contiguous to said cylindrical wall, said counterbore receiving a protection dish said bottom wall comprising a bore configured to allow the passage of a body of an assembly screw, said protection dish having an axial cross-section about an axis having the shape of a U, and comprising an annular wall of the axis comprising a bore configured to allow the passage of said body of the assembly screw and a cylindrical rim of the axis connected to an outer periphery of said annular wall,

• wherein said protection dish is configured to be deformed in response to an axial stress of a predetermined intensity applied on the annular wall thereof, from a first state to a second state, the cylindrical rim having a first transverse dimension relative to the axis,
• wherein when the annular wall is deformed, the cylindrical rim has a second transverse dimension relative to the axis that is greater than the first transverse dimension along a transverse direction determined relative to the axis,
• wherein the rim comprises two axial slits, aligned in a transverse plane that passes through the axis and that is perpendicular to the transverse direction, said slits dividing said rim into two half-cylindrical walls of a diameter equal to the second transverse dimension and each said slit extending at least to the periphery of the annular wall, and the annular wall is deformable in said transverse direction from an initial state, associated to the first state of the dish, to a final state associated to the second state of the dish,
• wherein the annular wall has the first transverse dimension, and the second transverse dimension, and
• wherein the first dimension and the predetermined diameter are arranged relative to each other with a first clearance therebetween providing a sliding fit between the rim and the cylindrical wall, and the second dimension and the predetermined diameter are arranged relative to each other with a second clearance therebetween providing a non-sliding fit between the rim and the cylindrical wall.