Mitsubishi MU-2B Safety Record

THE FATIGUE CRACKING AND FRACTURE OF THE PROPELLER HUB ARM. THE RESULTANT SEPARATION OF THE HUB ARM AND THE PROPELLER BLADE DAMAGED THE ENGINE, NACELLE, WING, AND FUSELAGE, THEREBY CAUSING SIGNIFICANT DEGRADATION TO AIRCRAFT PERFORMANCE AND CONTROL THAT MADE A SUCCESSFUL LANDING PROBLEMATIC. THE CAUSE OF THE PROPELLER HUB ARM FRACTURE WAS A REDUCTION IN THE FATIGUE STRENGTH OF THE MATERIAL BECAUSE OF MANUFACTURING AND TIME-RELATED FACTORS (DECARBURIZATION, RESIDUAL STRESS, CORROSION, MIXED MICROSTRUCTURE, AND MACHINING/SCORING MARKS) THAT REDUCED THE FATIGUE RESISTANCE OF THE MATERIAL, PROBABLY COMBINED WITH EXPOSURE TO HIGHER-THAN-NORMAL CYCLIC LOADS DURING OPERATION OF THE PROPELLER AT A CRITICAL VIBRATION FREQUENCY (REACTIONLESS MODE), WHICH WAS NOT APPROPRIATELY CONSIDERED DURING THE AIRPLANE/PROPELLER CERTIFICATION PROCESS.

THE FAILURE OF THE PILOT TO EXERCISE ADEQUATE VFR DEPARTURE TERRAIN AVOIDANCE PROCEDURES, AND THE FAILURE OF THE CONTROLLER TO ISSUE A SAFETY ALERT TO THE PILOT. FACTORS WHICH CONTRIBUTED TO THE ACCIDENT WERE: THE PILOT'S LACK OF FAMILIARITY WITH THE GEOGRAPHIC AREA, THE DARK NIGHT, AND THE MOUNTAINOUS TERRAIN.

AN INADVERTENT STALL DURING AN INSTRUMENT APPROACH WITH THE AUTOPILOT ENGAGED. A FACTOR WAS: THE PILOT'S PHYSICAL IMPAIRMENT FROM A PRESCRIPTION DRUG.

THE PILOT'S FAILURE TO MAINTAIN DIRECTIONAL CONTROL OF THE AIRPLANE AFTER BECOMING SPATIALLY DISORIENTED. FACTORS RELATED TO THE ACCIDENT WERE: DARKNESS, LOW OVERCAST CLOUD CONDITION, THE PILOT'S DECISION TO CONTINUE VFR FLIGHT INTO INSTRUMENT METEOROLOGICAL CONDITIONS (IMC), WHICH RESULTED IN A NEAR COLLISION WITH ANOTHER AIRCRAFT, HIS SELF INDUCED PRESSURE AND DIVERSION OF ATTENTION, WHILE COPING WITH THE SITUATION THAT HE HAD ENCOUNTERED.

THE SHUTDOWN OF ONE ENGINE FOR UNDETERMINED REASONS, AND THE PILOT'S FAILURE TO MAINTAIN VMCA DURING A CRITICAL PHASE OF FLIGHT. A FACTOR IN THE ACCIDENT WAS THE PILOT'S IMPROPER EMERGENCY PROCEDURE.

THE COMPANY/OPERATOR MANAGEMENT'S DECISION TO OPERATE THE AIRCRAFT WITH A KNOWN DEFICIENCY WITHOUT FURTHER MAINTENANCE, THE PILOT'S IMPROPER PLANNING/DECISION AND THE PILOT'S FAILURE TO ABORT THE TAKEOFF (WHILE THERE WAS SUFFICIENT RUNWAY REMAINING). FACTORS RELATED TO THE ACCIDENT WERE: LACK OF POWER IN THE RIGHT ENGINE, AND THE UNFAVORABLE METEOROLOGICAL CONDITIONS AT THE AIRPORT.

IMPROPER PLANNING/DECISION BY THE PILOT, WHICH RESULTED IN EXCESSIVE ACCUMMULATION OF STRUCTURAL ICING (ON THE AIRCRAFT'S WINGS, STABILIZERS, FUSELAGE, AND/OR ENGINE INLETS), AND HIS FAILURE TO MAINTAIN ADEQUATE AIRSPEED AND AIRCRAFT CONTROL. FACTORS RELATED TO THE ACCIDENT WERE: THE PILOT'S INADEQUATE WEATHER EVALUATION DUE TO LACK OF AVAILABLE INFORMATION AT THE AUTOMATED FLIGHT SERVICE STATION (AFSS), HIS FAILURE TO OBTAIN ADDITIONAL INFORMATION FROM OTHER WEATHER STATIONS (EITHER BEFORE TAKEOFF OR DURING THE FLIGHT), HIS LACK OF EXPERIENCE IN THIS MAKE AND MODEL OF AIRCRAFT, AND ICING CONDITIONS AT CRUISE ALTITUDE.

FAILURE OF THE PILOT TO MAINTAIN ADEQUATE AIRSPEED (VMC), WHICH RESULTED IN A LOSS OF AIRCRAFT CONTROL. A FACTOR RELATED TO THE ACCIDENT WAS: FATIGUE FAILURE OF A COUPLING SHAFT IN THE #1 ENGINE, WHICH RESULTED IN LOSS OF POWER IN THAT ENGINE.

FAILURE OF THE PILOT TO MAINTAIN CONTROL OF THE AIRCRAFT, DUE TO SPATIAL DISORIENTATION, AT ABOUT THE TIME HE WAS CHANGING RADIO FREQUENCIES DURING AN IFR APPROACH.