TM  10-3930-669-20 WARNING Drive axle and oil retains extreme heat.  Do not check oil until drive axle has cooled.  Failure to do so will result in severe bums to personnel. BRAKE DISC CHECK (1) Remove   check/fill   plug   (LO   10- 3930-669-12). (2) Measure brake disc thickness. (a)   If brake discs are not 0.079 in. (2   mm),   drive   axle   is   faulty. Perform   Step   (3)   below   and notify DS Maintenance. (b)   If brake discs are 0.079 in.  (2 mm) or less, drive axle is OK. (3) Install drive axle check/fill plug. 2-345