Airbus 300-600 N7082A

Summary

On 11 May 1999 at about 18:45 local time, a Airbus 300-600 registered N7082A, operated by American Airlines, was involved in an incident near Miami, Florida, United States. 129 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

11 May 1999 at 18:45

Classification

Incident

Location

Miami, Florida, United States

Coordinates

Not recorded

Aircraft

Airbus 300-600

Registration

N7082A

Category

Airplane

Operator

American Airlines

Operating rule

Part 121: Air Carrier

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Bogota → Miami

Aircraft damage

Not recorded

Weather

VMC

Light

Not Reported

NTSB number

DCA99IA058

Nobody was injured.

Uncommanded rudder movement caused by a contaminant in the engagement valve solenoid that prevented disengagement of the autopilot yaw actuator and cross-connected wiring of the autopilot yaw actuator's main valve solenoids by the operator. Factors contributing to the incident were the lack of proper controls in the solenoid assembly process and the lack of procedures to detect miswired solenoids.

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

Read the full NTSB narrative

During final approach to the airport and after the crew turned the autopilot off, American Airlines flight 916 began experiencing uncommanded rudder motion and high rudder pedal forces. The flight crew executed a go-around about 360 feet above ground level. Despite continued difficulties with the rudder, the flight crew was able to land the airplane successfully. Examination of the autopilot yaw actuator revealed two main findings: (1) the wiring to the two main valve solenoids had been cross connected, and (2) a foreign-particle contaminant in the green system engagement valve solenoid had prevented disengagement of the yaw actuator. Investigators found that when these two conditions exist, turn coordination system inputs can cause uncommanded rudder movements. Inspections of A300 and A310 airplanes after the incident resulted in the discovery of another American A300 with cross-connected solenoid wiring. American indicated that it had installed new autopilot actuator solenoids on this airplane and the rest of its A300 fleet. At the time the solenoids were installed, American's procedures did not include a check for proper installation of the solenoid wiring. The manufacturers of the airplane and the actuator have since incorporated new procedures to ensure that the solenoids are wired properly. As part of the investigation, numerous additional solenoids were examined for the presence of contaminants. Although contaminants were discovered on several other solenoids, they were smaller than that found on the incident airplane's engagement solenoid and did not affect solenoid functionality. Audits of the solenoid assembly process revealed the need to update production and inspection documentation and the need to include measures to prevent foreign particles from contaminating adjacent workstations. The manufacturer of the solenoids took corrective actions that included improving production facilities, implementing more stringent sampling and inspection procedures, and clarifying assembly instructions.

Quoted verbatim from the NTSB record.