DASSAULT/SUD FAN JET FALCON near Shreveport, LA — 2014-12-12

Probable cause

A short in the trim system’s wires and connector, which resulted in the elevator trim being in a full nose-down position.

NTSB narrative

According to the operator, during the visual approach, the copilot needed to use "more aft pressure than normal" while descending the airplane from 2,000 to 20 ft above ground level (agl). When the airplane was below 20 ft agl and in the landing flare, the yoke hit the aft stop. The flight crew subsequently landed the airplane without incident. After landing, the flight crew conducted a postflight examination, which revealed that the elevator trim was in the full nose-down position and that it could not be returned to the takeoff or neutral position. The flight crew pulled the circuit breaker and used the emergency trim to move the elevator trim to the takeoff position. After the trim circuit breaker was reengaged, the elevator trim moved back to the full nose-down position. Examination of the trim system found that a wire had shorted between two terminal junctions, which resulted in power at one of the terminal junctions regardless of the position of the trim switch on the captain's control. Further examination also found that the connector at another terminal junction had shorted. The wires and connectors were removed and replaced, and the trim anomaly was resolved.

Analysis

Primary failure mode

Mechanical failure

First missed decision gate

Co-pilot could have aborted the approach due to control issues before landing.

NTSB coding

• Flight control sys malf/fail · Approach-IFR final approach

Evidence available

• 1 docket document

Docket documents1

• Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1form