1.1 This International Standard provides a design for quick-release couplings with involute spline drive, intended primarily for aircraft engine/gearbox accessories which require to be removed whilst the engine/gearbox is in service. 1.2 This International Standard comprises — clauses 3 to 12 : Design notes and recommendations; — figure 1/tables 1a) to 1e) : Accessory flanges up to spigot reference 250; — figure 2/tables 2a) to 2d) : Engine/gearbox pads up to spigot reference 250; — figure 3/tables 3a) to 3e) : Accessory flanges above spigot reference 250; — figure 4/tables 4a) to 4e) : Engine/gearbox pads above spigot reference 250; — figure 5/tables 5a) and 5b) : Coupling clamps; — figure 6/tables 6a) and 6b) : Selected involute splines. 1.3 Items subject to agreement between engine/gearbox manufacturer and accessory manufacturer are listed in an annex.