Ahah, everyone is bitchin' about the image istead of focusing on the problem!

What you have there is a missing fx texture. Try reinstalling the plane. If it doesn't work, add the default strobe effect in the aicraft.cfg file:
[lights]
replace the name of the strobe effect in the strobe light line for "fx_strobeh.fx"
if the navigation lights are also faulty, replace them with fx_navgre (green port light), fx_navred (red starboard light), fx_navwhi (white tail light)