Maintenance Access Cover of Bölkow 207. While these covers are essential for maintenance and inspection tasks, they are generally not utilized by pilots. This cover is specifically designed for the Bölkow 207 from the 1960s. The component, which features a quick-release fastener comes in both round and oval shapes, are installed in the fuselage or wings to provide mechanics and inspectors access to control levers and rods. The aluminum covers are coated with zinc chromate, a traditional primer used to prevent corrosion.