Advanced　asset　management　emphasizes　the　collaborative　schemes　of　maintenance　and　spare　part　resources　driven　by　asset　health　status.　This　paper　formulates　a　joint　optimization　model　of　maintenance-spare　part　provisioning　policy　for　a　production　system　with　observable　defect　information　and　postponed　spare　part　supplies.　Three　levels　of　state-based　maintenance　windows,　(a)　regular　inspection　window　(RIW);　(b)　defect　removal　window　(DRW),　and　(c)　pre-specified　overhaul　window　(POW)　are　integrated　to　promote　the　timeliness　and　robustness　of　maintenance　decision-makings,　and　mitigate　production　downtime　due　to　spare　part　delays.　In　particular,　a　spare　part　order　is　induced　upon　defect　identifications　at　DRW　and　the　system　continues　production　until　being　replaced　as　soon　as　the　order　arrives　at　the　maintenance　base,　or　being　renewed　at　POW　when　the　system　attains　a　specified　age.　As　such,　spare　part　replacement　is　delayed,　so　as　to　leave　enough　time　for　resource　preparation,　and　prolong　the　remaining　useful　lifetime.　The　system　net　profit　is　maximized　through　the　interval　optimization　of　RIW　and　DRW.　A　numerical　experiment　on　maintenance　engineering　of　a　steel　convertor　plant　is　used　to　demonstrate　the　proposed　methodology.