THE ACFT WAS VECTORED TO INTERCEPT THE LOCALIZER COURSE FOR AN ILS APPROACH TO RWY 10 AT BALT-WASH-INTL ARPT. IT WAS THEN OBSERVED TO FLY THROUGH & TO THE NORTH OF THE LOCALIZER COURSE. THE ACFT WAS THEN DIRECTED TO TURN LEFT TO A HEADING OF 360 FOR RESEQUENCING, HOWEVER THE ACFT WAS OBSERVED MAKING A 360 TO THE RIGHT. THE ACFT WAS TRACKED BY THE RADAR COMPUTER IN A RIGHT TURN, COMPLETING ALMOST 360 DEG OF TURN WITH A STEADY GROUNDSPEED DECAY ACCOMPANIED BY ERRATICALTITUDE EXCURSIONS. THIS WAS FOLLOWED BY AN ABRUPT COURSE REVERSAL, RAPID GROUNDSPEED DECAY, & CONTINUED ERRATIC ALTITUDE EXCURSIONS. THE ACFT CRASHED INTO A HOUSE IN A RESIDENTAL SECTION OF COLUMBIA IN AN INVERTED POSITION. THE ACFT'S AFT CG LIMIT WAS EXCEEDED. THIS WOULD RESULT IN A DETERIORATION OF THE ACFT'S DYNAMIC STABILITY WHICH WOULD PRODUCE EXAGGERATED ACFT REACTIONS TO OTHERWISE NORMAL CONTROL DISPLACEMENT INPUTS. THE PLT HAD NOT LOGGED ANY INSTRUMENT TIME OR INSTRUMENT APPROACHES DURING THE SIX MONTHS PRECEEDING THE ACCIDENT.