AD NUMBER: 2011-02-09

MANUFACTURER: Airbus Model A330-200 Series Airplanes; Model A330-300 Series Airplanes; Model A340-200 Series Airplanes; and Model A340-300 Series Airplane
SUBJECT: Airworthiness Directive 2011-02-09

SUMMARY: This AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
When there are significant differences between all airspeed sources, the flight controls of an Airbus A330 or A340 aeroplane will revert to alternate law, the autopilot (AP) and the auto-thrust (A/THR) automatically disconnect, and the Flight Directors (FD) bars are automatically removed.
It has been identified that, after such an event, if two airspeed sources become similar while still erroneous, the flight guidance computers will:

• Display FD bars again.
• Enable autopilot and auto-thrust re-engagement.

However, in some cases, the autopilot orders may be inappropriate, such as possible abrupt pitch command.

The unsafe condition is the potential for abrupt pitch command which may lead to unexpected maneuvers of the airplane and cause injuries of the crew and passengers, as well as reduced controllability of the airplane, and increased pilot workload.

FMI: http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgAD.nsf/0/11E48BEB5C6AD22F86257823004DA34A?OpenDocument