Thank you for selecting Aerospace Aviation360 as your go-to distributor of part number NO PRIMARY REF 99 257 8571 found under Datum Plug Assembly by This Ncage Is Used To Inform That. The National Stock Number assigned to this part is 2925992578571, and the Federal Supply Class is 2925 Engine Electrical System Components Aircraft Prime Moving. Our website is owned and operated by ASAP Semiconductor, a leading distributor of aviation and aerospace part numbers like NO PRIMARY REF 99 257 8571.