A KC-135 flight crew suffered the loss of all three MFD map displays while performing a refueling mission. A temporary departure from the charted refueling airspace occurred while they reoriented themselves and regained use of the NAV displays.

Narrative

The autopilot was engaged in NAV/LOC with a closed random pattern depicted in the flight plan following the four points forming the air refueling track within R2501. We were approximately 5-10 miles from the western border of R2501; headed west; and all three MFD's in MAP mode displayed aircraft within R2501 on a westbound course with a turn southbound ahead.All systems remained normal with no faulty indications when we suddenly lost all three MFD map displays; which all went blank and displayed 'MAP FAIL' indications. I asked the Boom [Operator] to reference an independent laptop with GPS guidance; which displays a moving map of the aircraft purely for aircrew situational awareness. The Boom [Operator] pulled up the moving map display; which showed the aircraft outside of R2501 to the west. I immediately initiated a turn back towards the east by reference to a ground point we were familiar with from previous orbits and magnetic compass heading.After a short troubleshooting session; we were able to regain our HDG; NAV system; and map displays on all three MFD's by proceeding direct to another point in the flight plan. We disengaged the NAV/LOC on the autopilot and navigated the rest of our mission off of the map displays while cross checking the separate laptop GPS moving map. There is no guidance within the KC-135 technical orders for a 'MAP FAIL' indication. There is; however; a safety supplement for the KC-135 block 40.1 navigation software for a frozen HDG/NAV system failure. While we agree we had a frozen HDG/NAV system failure; our indications within the cockpit did not match the safety supplement and the safety supplement did not mention any 'MAP FAIL' annunciation.There were no air traffic control conflicts which occurred during our 'spill-out' of R2501 and LA Center logged the event as a 'spill-out.' This was an extremely alarming event to the aircrew; especially based on the lack of before and after system failure reports. There was absolutely no warning other than the 'MAP FAIL' which only showed after the failure had already been occurring in the system; all while the auto-pilot remained coupled to the failed NAV system. Even after we were able to get the MFD's back there were no indications of any failure; no BIT codes; no faults; etc. The only CDU annunciation was a 'check CP GPS;' which we did and found all NAV systems in the green with minimal drift. We have reported this malfunction to aircraft Maintenance.