NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

DRG TKOF, AS USAIR FLT 224 WAS CLBG THRU 4000', THE ACFT YAWED/ROLLED RGT. SIMULTANEOUSLY, THE CREW NOTICED THE #2 THROTTLE SLAM/LOCK TO THE IDLE PSN & A CONTINUOUS AIRFRAME BUFFET BEGAN. SOON THEREAFTER, THE #2 ENG SEPD FM THE ACFT & THE BUFFET STOPPED. THE ENG IMPACTED IN AN OPEN FLD, 6 MI FM THE ARPT. JUST BFR IT SEPD, A PAX SAW THE AFT END OF THE #2 ENG MOMENTARILY DROOP ABOUT 30 DEG. AFTER ENG SEPN, THE 'B' HYD SYS LOST PRES & THE TE FLAPS WOULD ONLY EXTD 10 DEG. THE ACFT WAS LNDD SAFELY AFTER AN EMERG GEAR EXTN & DIFFERENTIAL BRAKING WAS USED FOR STEERING. AN EXAM REVEALED THE AFT MOUNT CONE BOLT FOR THE #2 ENG HAD FAILED FM FATIGUE THRU THE THREAD RELIEF UNDERCUT RADIUS. FATIGUE CRACKS HAD INITIATED ON DIAMETRICALLY OPPOSITE SIDES OF THE RADIUS. SUBSEQUENTLY, THE FWD MOUNT CONE BOLTS & SECONDARY SUPPORT CABLE FAILED FROM OVERLOAD.