Another A330 Pitot Tube Incident?

A Jetstar Airways Airbus A330-200 on Oct. 29 may have suffered the same malfunction involved in the loss of an Air France jetliner over the Atlantic, killing all on board, five months ago.

The Jetstar Airways A330-200 with 209 passengers and crew onboard suffered momentary erratic speed data indications from its computers in apparent bad weather and possible icing conditions on the flight from Tokyo Narita to Gold Coast.

The scenario bears similarities to that which investigators believe may have been a factor in the loss of Air France Flight 447, an Arbus 330-200, over the Atlantic Ocean on June 1.

The pilots of Flight JQ12 remained in control when the situation occurred and the malfunction cleared after a few seconds. The pilots landed at Gold Coast around five hours later and passengers reportedly were unaware of any problem.

A Jetstar spokesperson reportedly confirmed the incident and said the problem appeared to relate to the aircraft's speed-sensing system, which involves pitot tubes and air data inertial reference units. "At this early stage we don't know which component caused the problem," the spokesperson said.

In the wake of the Air France fatal accident, Airbus issued various directives to A330 and A340 operators relating to pitot tubes and suggested the replacement of at least two Thales probes with Goodrich models Both Qantas and Jetstar A330s are fitted with Goodrich tubes.

The Australian Transport Safety Bureau (ATSB) and the Civil Aviation Safety Authority are investigating the incident.

The ATSB has yet to determine what caused a violent upset of a Qantas A330 off Western Australia in October 2008, injuring 75.

The in-flight upset occurred on Oct. 7 and involved a Qantas Airbus A330-303 (QF72). The aircraft abruptly pitched nose-down twice while in normal cruise flight. The aircraft (VH-QPA) was on a scheduled passenger service from Singapore to Perth. While cruising at 37,000 ft, the aircraft experienced two significant uncommanded pitch-down events while responding to various system failure indications. The crew made an urgency broadcast to air traffic control and requested a clearance to divert to and track direct to Learmonth. After receiving advice from the cabin of several serious injuries, the crew declared a mayday. The aircraft landed at Learmonth without further incident.

The investigation to date has identified two significant safety factors related to the pitch-down movements.

First, immediately prior to the autopilot disconnect, one of the air data inertial reference units (ADIRUs) started providing erroneous data (spikes) on many parameters to other aircraft systems. The maintenance post-flight report from the aircraft's central maintenance computer and built-in test equipment (BITE) data for several systems indicated a problem with ADIRU 1, but no data indicated a problem with ADIRU 2 or ADIRU 3. Testing of other relevant systems and components identified no problems with these systems or components, which were related to the circumstances of the occurrence.

Second, some of the spikes in angle of attack were not filtered by the aircraft's flight control computers. The A330 used a variety of redundancy and error-checking mechanisms to minimize the probability of erroneous ADIRU data having a detrimental effect on the aircrafts flight controls. On the A330, angle of attack data was processed differently to other parameters and, in a very specific situation, the flight control computers could generate an undesired pitch-down elevator command. The aircraft manufacturer reported that it was not aware of any previous event where angle of attack spikes had resulted in an in-flight upset.

The three ADIRUs from the aircraft were sent to Northrop Grumman, the ADIRU manufacturer, for testing.