A semiconductor device is provided, which includes a single crystal semiconductor layer formed over an insulating surface and having a source region, a drain region, and a channel formation region, a gate insulating film covering the single crystal semiconductor layer and a gate electrode overlapping with the channel formation region with the gate insulating film interposed therebetween. The flame sensor may activate an electric switch connecting the power supply to the respective light emitter. A feed tube is fastened to the nose cone of the engine.