Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 251A1639-1 found under Nrp Bearing Aileron by The Boeing Company. The National Stock Number assigned to this part is 1680016099143, and the Federal Supply Class is 1680 Miscellaneous Aircraft Accessories And Components. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 251A1639-1.