AUCKLAND- Air New Zealand (NZ) faced an in-flight engine shutdown on an Airbus A320 after a defective fire switch triggered an emergency diversion to Auckland (AKL). The Transport Accident Investigation Commission says similar faults have appeared across multiple aircraft, raising questions about how many units may be affected.
The incident occurred on a Wellington (WLG) to Sydney (SYD) service when the crew detected a loud clicking sound, followed by a loss of thrust. Investigators later traced the problem to internal damage in the fire switch mechanism.
Air New Zealand A320 Defective Switch
The inquiry found that the December 2024 shutdown on Flight NZ249 was one of several cases where damaged or misaligned fire switches caused unintended activation. In total, up to six known events have involved Airbus A320 family aircraft operating with a faulty or deformed switch assembly.
Detailed inspections after the diversion showed that the number two engine fire switch was protruding from its panel in the activated position.
This switch is designed to cut fuel and arm fire extinguishers during an engine fire, but in these cases, it activated without crew input. Investigators confirmed that neither pilot had touched the switch, and standard procedures did not direct them to inspect it.
Airbus advised that similar events had occurred on flights between Milan and Lisbon and in earlier incidents dating back to 2016. All were linked to panel deformation and issues with pin-locking systems inside the switch assembly, RNZ reported.
How the Fault Developed
Technicians found that the guard covering the Air New Zealand switch and the surrounding panel were bent out of shape. The retention pin that secures the mechanism was also damaged and incorrectly positioned. These defects made the switch prone to popping out during flight.
The manufacturer had already issued service bulletins for 125 panels in circulation, recommending removal and inspection. These applied only to previously repaired units that could show external damage but had not been checked for internal faults.
After the Air New Zealand event, another aircraft experienced the same issue despite its panel not being listed in the bulletin batch.
Regulatory Actions
Airbus later issued broader guidance covering all A320 family aircraft with visible panel damage, classed as a recommended action to be completed within 1000 flight cycles.
The European Union Aviation Safety Agency followed with a directive in which any damaged panel must be replaced within six months.
The Civil Aviation Authority of New Zealand pointed out that the true scope of the problem remained unclear. In response, Air New Zealand removed suspect panels fleetwide and sought clearer inspection criteria from the manufacturers and service agents.
Extent of Impact Across the A320 Fleet
The A320 remains the world’s most widely used single-aisle jet with more than 11,500 delivered.
The recent attention on the type, including concerns over solar radiation effects on flight control elements, has focused regulators and operators on component integrity.
The TAIC report notes that further investigation is required to understand how many switches across the global fleet may still carry the internal defects linked to spontaneous activation.
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