Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number 18500-331 found under Worm Assy by Flowserve Corporation. The National Stock Number assigned to this part is 4810012254293, and the Federal Supply Class is 4810 Valves Powered. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like 18500-331.