THE BEECH 58 PLT WAS RETURNING AT NGT WHEN TRAFFIC WAS VERY LIGHT. AFTER LNDG, THE ACFT WAS RETAINED ON LOCAL CONTROL (LC) FREQ FOR THE PLT'S CONVENIENCE. THE PLT REQUESTED CLNC TO THE TWA HANGAR & WAS CLEARED ON THE MOST EXPEDITIOUS ROUTE. THIS ROUTE WENT NEXT TO THE RWY 9L PAD, WHERE A BOEING 747 MAINT CREW WERE RUNNING UP/TRIMMING ENGS. THE BEECH WAS BLOWN OVR AS IT PASSED BEHIND THE BOEING. DURING THE OCCURRENCE, THE TOP OF THE BEECH WAS CRUSHED INWARD, FATALLY INJURING THE PLT. TOWER LETTER OF OPNS PROHIBITED THE USE OF TAXIWAY NEXT TO THE RWY 9L PAD, WHEN IT WAS BEING USED FOR RUN-UPS. THE BEECH PLT WAS NOT CAUTIONED ABOUT PSBL WAKE TURBC & THE BOEING CREW WERE NOT ADVISED OF THE BEECH'S PSN. FOR REASONS OF NOISE ABATEMENT, THE NGT-TIME RUN-UP OF THE BOEING 747 SHOULD HAVE BEEN CONDUCTED ON A HDG OF EAST OR NORTHWEST, BUT THE 747 WAS ON A HDG OF SOUTHWEST, ANGLED INTO THE WIND. NONE OF THE FOUR TOWER CONTROLLERS DETECTED OR ATTEMPTED CORRECTING ITS ORIENTATION.