Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 140-007-21-17A4 found under Washer Recessed by Bell Helicopter Textron Inc. The National Stock Number assigned to this part is 5310010164873, and the Federal Supply Class is 5310 Nuts And Washers. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 140-007-21-17A4.