Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number B4U12-3 found under Cover Dust Valve by Transdigm Inc. The National Stock Number assigned to this part is 2995013091903, and the Federal Supply Class is 2995 Miscellaneous Engine Accessories Aircraft. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like B4U12-3.