Accident · 1991-03-03

NTSB case DCA91MA023 · BOEING 737-291 · Part 121

What the record says

Event date: 1991-03-03
Event type: Accident
Highest injury level: Fatal injury
Aircraft: BOEING 737-291 (N999UA)
Operating rule: Part 121
Operator: UNITED AIRLINES, INC. Operator named in NTSB report
Operated by (per NTSB report): UNITED AIRLINES

Probable cause

A loss of control of the airplane resulting from the movement of the rudder surface to its blowdown limit. The rudder surface most likely deflected in a direction opposite to that commanded by the pilots as a result of a jam of the main rudder power control unit servo valve secondary slide to the servo valve housing offset from its neutral position and overtravel of the primary slide.

Source: NTSB case DCA91MA023

Flight crew

Flight-crew details for this event aren't in the NTSB database extract we hold (its coverage starts with 2008 events) — a gap in our data, not an absence of crew.

Facts as the NTSB records them — GroundCheck adds no judgement. Preliminary records may be revised as the investigation proceeds.

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