Although the wide range of ball nut screws used in the industry are commercial types available in the market, they are not limited to this category. In fact, there is another category that require non-standard special design with specific geometric shapes and pitches for distinctive conditions and cannot be developed by relying on the design standards or the existing catalogs. Focusing on this latter class of ball-nut-screws, ASA Company specializes in designing and manufacturing this product in limited capacity to address the MTO domestic demands in this field. Ball-nut-screws play an important role in sensitive systems such as landing Gear system and control of aircraft wing flaps as require the extraction of design technical knowledge considering the static, vibrationl and dynamic parameters of the entire system. Examples of ball-nut-screws studied by engineering team at ASA Company include those used in aircraft rear wheel landing gear system and wing flap controller. Due to high sensitivity of noted applications, these parts, as mechanical actuators convert the rotational motion of the motor into linear motion, must remaining highly reliable with minimum noise and vibration in the system in addition to meeting the common technical challenges of designing and manufacturing commercial types. Another challenge in designing this class of ball-nut-screws is the internal thread grinding which is performed to increase reliability, reduce friction and prevent extra increase of clearance. This indicates the importance of the design and R&D processes, especially in case of sensitive mechanical aeronautical equipment.