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CHI89MA047

1989-01-20 · SOUTH BEND, Indiana, United States · None · 1 aircraft · Status: Completed

Airport SBN

N901B has since been reassigned. It is now registered to a different aircraft (AEROSPATIALE SA341G GAZELLE, built 1977), which was not involved in this event.

Aircraft involved

Probable cause & findings

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.

Factual 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. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12

Verbatim from NTSB's published report. Source file NTSB_1989_CHI89MA047.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.