# NTSB Incident DCA96IA061
> **Boeing B-737-201** · 1996-06-10 · RICHMOND, VA, USA · NONE
## Event
- **NTSB number:** DCA96IA061
- **Event ID:** 20001208X05950
- **Type:** Incident
- **Date:** 1996-06-10
- **Location:** RICHMOND, VA, USA
- **Coordinates:** 37.440887, -77.320114
## Injuries
- **Highest injury:** NONE
- **Fatal:** 0
- **Serious:** 0
- **Minor:** 0
- **Uninjured:** 53
- **Total aboard:** 53
## Aircraft
- **Make:** Boeing
- **Model:** B-737-201
- **Registration:** N221US
- **FAR Part:** 121
- **Engines:** —
- **Damage:** —
## Conditions
- **Light:** NR
- **Weather:** VMC
## Probable cause

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.

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*Source: [NTSB CAROL](https://data.ntsb.gov/carol-main-public/basic-search?source=ntsb&type=event&ntsb_number=DCA96IA061) · MORVS · CC0 1.0*