The shutter has a rolling shaft (4) driven in rotation to operate an apron (1) between rolled and deployed positions. A sealing joint (6) made of elastomer is carried by an aluminum longitudinal end blade (L'') of the apron. The blade is near a longitudinal passage slit (3) of a protection case (2) in the rolled position. The apron closes an opening (100), and the blade is opposite to the case in the opening in the deployed position. The blade and the slit are conformed such that the blade closes the slit when the apron is in the rolled position.