Accident Dassault Falcon 900 N901B, Friday 20 January 1989

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Date:	Friday 20 January 1989
Time:	10:14 LT
Type:	Dassault Falcon 900
Owner/operator:	Bristol-myers Co.
Registration:	N901B
MSN:	024
Total airframe hrs:	886 hours
Engine model:	GARRETT TFE-731
Fatalities:	Fatalities: 0 / Occupants: 4
Other fatalities:	0
Aircraft damage:	Substantial
Category:	Accident
Location:	South Bend, IN - United States of America
Phase:	Landing
Nature:	Executive
Departure airport:	Philadelphia, PA (PHL
Destination airport:
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
THE PLTS RPRTD THAT WHILE LNDG ON A SNOW & SLUSH CVRD RWY, THEY USED FULL REVERSE THRUST & MAX BRAKING WITH ANTI-SKID, BUT THE ACFT DID NOT DECELERATE. THEY SELECTED THE #2 BRAKE SYS WITHOUT ANTI-SKID. SUBSEQUENTLY, THE MAIN TIRES FAILED (BLEW-OUT) & THE ACFT SLID OFF THE LEFT SIDE OF THE RWY, COLLAPSING THE LEFT MAIN GEAR. INV REVEALED THAT BOTH THRUST REVERSER ACTUATOR LINKS ON THE #2 ENG HAD FAILED. WITH THESE FAILURES THE #2 ENG WOULD HAVE CONTD TO PROVIDE FWD THRUST,PROPELLING THE ACFT DWN THE RWY. (ON THIS MODEL OF ACFT, ONLY THE #2 ENG WAS EQUIPPED WITH REVERSE THRUST CAPABILITY.) METALLURGICAL EXAMS OF THE FWD ROD END FITTINGS OF BOTH REVERSE THRUST ACTUATOR LINKS (P/N 8140-06LK) REVEALED THE BEARING LOOPS HAD FAILED FROM OVERSTRESS. MANDATORY SERVICE BULLETIN (S/B) F900-78-1 WAS ISSUED ON 5/18/89 TO PROVIDE A SAFETY SYSTEM TO PREVENT ACTIVATION OF THE THRUST REVERSER ABOVE IDLE, WHILE THE AIRCRAFT IS ON THE GROUND. ALSO, MANDATORY S/B F900-78-2 WAS ISSUED ON 7/19/89 TO REINFORCE THE THRUST REVERSER ACTUATING MECHANISMS.

Probable Cause: FAILURE OF THE THRUST REVERSER ACTUATOR LINKS DUE TO A MANUFACTURING/DESIGN PROBLEM. FACTORS RELATED TO THE ACCIDENT WERE: THE ADVERSE RUNWAY CONDITIONS AND THE CROSSWIND.

Accident investigation: