What happened
On 7 September 2002, an Airbus A-340, registration EC-IDF, was landing on runway 33 at Madrid-Barajas Airport when a series of tire bursts caused the aircraft to deviate from the runway centerline. The flight, which had originated from Tenerife Norte, had been operating with a known hydraulic anomaly. During the approach, the crew observed indications of residual pressure in the brakes of the left main landing gear on the ECAM WHEEL page. Because this indication was not accompanied by a specific caution message, the crew suspected the reading might be spurious and elected to land with the antiskid system manually disconnected.
Upon touchdown, the pilot in command utilized reverse thrust and right rudder to maintain alignment, but the aircraft began to deviate. Between 240 and 900 meters from the runway threshold, the four wheels of the left main landing gear burst. The resulting loss of control caused the aircraft to veer initially to the right and then to the left. In an attempt to regain control, the crew applied heavy right braking, which caused the pressure in the right-side brakes to reach 2500 psi, subsequently leading to the burst of the four right wheels. The aircraft eventually came to a stop 5 meters from the edge of the runway asphalt, with the fuselage rotated approximately 10 degrees from the runway axis. A fire broke out affecting the landing gear wheels, which was suppressed by airport emergency services. There were no injuries to the 263 people on board.
The investigation
The investigation focused on the origin of the residual hydraulic pressure and the crew's decision-making regarding the antiskid system. Investigators examined the aircraft's maintenance history, the flight recorders, and the specific components of the braking system. Technical testing was conducted on the brake master cylinder and the dual valve (BDDV) to identify the source of the pressure. The investigation also reviewed the airline's operational manuals and training procedures regarding intermittent hydraulic faults.
Findings
- The primary cause of the residual pressure was a defective left master cylinder (S/N H2121) that possessed a dead band and length exceeding specified tolerances.
- The crew's decision to manually disconnect the antiskid system while residual pressure was present directly led to the burst of the left tires upon touchdown.
- There was a lack of specific operational procedures in the airline's manual for handling the observed residual pressure indication.
- The flight crew was not sufficiently aware of similar reported incidents from earlier that year.
- Training regarding the complexities of the A-340 brake system was found to be insufficient for managing such intermittent malfunctions.