EA30 CREW HAD ACFT OVERSPD AND DID NOT COMPLY WITH XING RESTR.

Narrative

PRIOR TO DSCNT ON MARVELL 3 ARR LOADED AND VERIFIED 325 KTS/12000 FT CONSTRAINT AT TAMMY. ALL FMS AND NAV DISPLAY INDICATIONS NORMAL. BEGAN DSCNT IN PROFILE MODE FROM FL330 AT TOD AND INSERTED .80 MACH/325 KT DSCNT SPD ON TACT PAGE AND ACTIVATED. DSCNT SHOWN AS 'ON PROFILE' WITH CORRECT NAV DISPLAY ARROWS UNTIL APPROX FL210. AT THAT POINT ACFT ABRUPTLY NOSED OVER AND RAPIDLY ACCELERATED TO 345 KTS WITH ASSOCIATED OVERSPD WARNINGS AND FLASHING 'MORE DRAG' INDICATION ON PFD. PROGRAM PAGE NOW SHOWED APPROX 6500 FT ABOVE PROFILE. SELECTED LEVEL CHANGE; EXTENDED FULL SPD BRAKES; SLOWED BELOW VMO AND CONTINUED DSCNT AT 330 KTS 'BANANA' IMMEDIATELY SHOWED THAT WE WOULDN'T BE ABLE TO REACH OUR ASSIGNED 12000 FT RESTR ALT AT TAMMY. INFORMED ZME OF OUR DILEMMA IMMEDIATELY. THEY DIDN'T SEEM ALARMED AND TURNED US OVER TO MEMPHIS APCH CTL. TO OUR KNOWLEDGE; NO LOSS OF SEPARATION WITH ANY OTHER ACFT OCCURRED. AGAIN; ALL FMS PROGRAMMING AND INDICATIONS WERE CORRECT AND STANDARDIZED UNTIL WE REACHED FL210 DURING DSCNT. I DETAILED THESE EVENTS IN THE ACFT MAINT LOG AND PERSONALLY DEBRIEFED THE MECH. I BRIEFED THE AIR OPS DUTY OFFICER AND SUBMITTED A COMPANY FLC SAFETY RPT AS WELL.