Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number UA538828-1 found under Valve Safety Relief by Triumph Thermal Systems Inc. The National Stock Number assigned to this part is 4820012626321, and the Federal Supply Class is 4820 Valves Nonpowered. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like UA538828-1.