Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number B31257 found under Fan Tubeaxial by Nidec Torin Corp. The National Stock Number assigned to this part is 4140015992161, and the Federal Supply Class is 4140 Fans Air Circulators And Blower Equipment. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like B31257.