The Service Bulletin provides the instructions for the inspection, and if required, repair of the elevator control torque tube for Sling 4 and Sling 4 TSi aircraft. Internal quality checks have shown that elevator control stop plates in some aircraft may have been installed with aluminium 3.2 x 8 mm domed rivets instead of stainless steel 3.2 x 8 mm domed rivets. These aluminium rivets shear at lower control stick loads compared to the stainless-steel rivets, so it must be ensured that stainless steel rivets are installed.