What is this class of bolts called? They can be seen in many —mainly military— jet engines. Do these bolts recibe an special name?


J79: the fasteners are everywhere

EJ200: they can be discerned in the rear flange
12 point flange cap bolt/screw. For high torque applications, less likely to be accidentally rounded-off. 
http://www.fbabolt.com.au/12-point-advantages.html