A removable device for attaching two mechanical parts includes a pin removably locking a first part with respect to a second part, a retainer member on the pin and a resiliently loaded tension member which collaborate to prevent the pin from coming out of its locked position; the removable device further includes at least two inclined surfaces, the general shape of which is that of a projection oriented in the axial direction of the pin, such that when the pin rotates, the retainer member runs along the inclined surfaces and the pin moves between the locked position and unlocked position against a force exerted on the pin along a longitudinal axial direction of the pin exerted by the tension member.