A B757-200's Mode Control Panel malfunctioned during descent causing the FMC's to dump; the autopilot and autothrottles to disconnect and the Mode Control Panel to blank. All functions returned to normal after a slight delay except for Radio Altimeter #2.

Narrative

During cruise after initial descent; left autopilot on; flight director switches on the flight directors operating; we received on EICAS alert for autopilot off/disengaged; autothrottles off/disengaged; both FMCs dumped all data. Mode control panel went blank. The problem seemed to be a power interruption; but both generators and the entire generator control panel were normal. Mode control panel came back on in approximately 2 minutes. Flight directors were turned off then on and seemed to work normally. The right autopilot was engaged and seemed to work normally. The FMC was re-loaded with closeout weights and the route. I initially flew the aircraft manually until the mode control panel and flight directors were re-established and the right autopilot was engaged. After this event; all systems seemed normal; except the First Officer radio altimeter was inoperative throughout the descent and landing. Both radio altimeters have a write-up history. After the event all EICAS messages went away and there were no status messages. I flew a visual approach to Runway 8 for an uneventful landing. The flight crew remained overnight on a scheduled turn. A B757 mode control panel was flown in. Mechanics did an excellent job fixing the aircraft. The crew was getting conflicting information from crew schedule versus the station. An approximate XJ15 local pick-up time was established as the whole crew had to be found and notified. The crew arrived at the airport approximately XK00 local. I was debriefed by the mechanics when I stepped out of the crew van. The return flight with the same aircraft was uneventful.