On Airbus aircraft, the undercarriage reinforcing is attached through the lower wing skin using bolts up to 1- inch in diameter through as much as a 4-inch stack up. This operation typically takes place in the wing box assembly jigs. Manual hole drilling for these bolts has traditionally required massive drill templates and large positive feed drill motors. In spite of these large tools, the holes must be drilled in multiple steps to reduce the thrust loads, which adds process time.
The GRAWDE (Gear Rib Automated Wing Drilling Equipment) is a wing-drilling machine specifically designed for operations in the gear rib area of the A380 wing. The machine drills fastener holes for the purpose of fastening the gear rib reinforcing through the skin into the rib spar structure matrix. Fastener holes in this area of the wing are as large as 1 inch in diameter and 4 inches deep. Manually cutting these large holes is a multi-step process using numerous pneumatic drill motors and drill templates. In the assembly jig, this area of the wing extends just below factory floor level. High fastener density, numerous drill motors and templates, and restricted worker access to the reinforcing area for the workers creates a rate-limiting step in the wing assembly process. The GRAWDE was designed to address these challenges.
The GRAWDE can precisely position countersunk fastener holes up to 1.25 inches in diameter through a 4- inch stack. It has the ability to re-synch to a feature on the wing or in the jig, drive to a precise location, adjust for normality and drill a hole in a single shot. It eliminates the use of pneumatic drill motors and templates. It reduces drilling time to less than one minute per hole, while producing superior quality holes. The mobility of this machine provides maximizing of a valuable capital asset over multiple parallel work zones.
When operating the GRAWDE, the operators stand on a moving platform 250 mm below factory floor and 500 mm above the machine beds. From the platform, operators can reach the wing surface, operator controls and quill box for changing tools. The platform has handrails and a gate on two sides, to protect the operator from falling and to protect from shear points between the GRAWDE and assembly jig components. Manual access can also gained by driving the GRAWDE away from the immediate area and standing directly on the machine bed.