Abstract: An apparatus for flameout detection to be used with a furnace having a sight hole tube for inspection of a flame. The apparatus comprises a fixed portion adapted for being mounted to the sight hole tube and being electrically connected to a control system. The fixed portion defines a first see-through channel being positioned opposite a sight hole of the sight hole tube, whereby the flame is visible therethrough. A detachable portion has a sensor device disposed therein a second see-through channel. The detachable portion is releasably mounted to the fixed portion such as to engage a contact connection therewith. The sensor device is disposed opposite the first see-through channel of the fixed portion for flameout detection therethrough, wherein the detachable portion is electrically disconnected upon being detached from the fixed portion.