Boeing B-737-201 N221US

Summary

On 10 June 1996 at about 02:00 local time, a Boeing B-737-201 registered N221US, operated by Eastwind Airlines, was involved in an incident near Richmond, Virginia, United States. 53 people were on board and nobody was injured. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

10 June 1996 at 02:00

Classification

Incident

Location

Richmond, Virginia, United States

Coordinates

37.4409, -77.3201

Aircraft

Boeing B-737-201

Registration

N221US

Category

Airplane

Operator

Eastwind Airlines

Operating rule

Part 121: Air Carrier

Purpose of flight

Unknown

Phase of flight

Not recorded

Aircraft damage

Not recorded

Weather

VMC

Light

Not Reported

NTSB number

DCA96IA061

Nobody was injured.

The yaw/roll upset 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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The Boeing 737-200 experienced a yaw/roll upset while operating at an airspeed of about 250 knots and an altitude of about 4,000 feet msl in visual flight rules (VFR) conditions. The pilots were able to regain control of the airplane and land at the destination airport without further incident. As a result of previous Boeing 737 rudder anomalies, including the fatal accident involving USAir flight 427, a Boeing 737-300, which entered an uncontrolled descent and impacted terrain near Aliquippa, Pennsylvania, on September 8, 1994, Safety Board investigators initiated an investigation into this incident. Investigators conducted detailed examinations of pertinent rudder control components, reviewed flight test data, performed a computer simulation, and completed an analysis of human performance data. As a result, the Safety Board concluded that the rudder reversed, moving to its right blowdown limit when the captain commanded left rudder, consistent with 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. The complete report of this incident investigation, including all analyses, is contained in the final report of the USAir flight 427 investigation which can be found on the NTSB web site at the following link: http://www.ntsb.gov/publictn/1999/AAR9901.pdf

Quoted verbatim from the NTSB record.