Transport Canada Civil Aviation (TCCA) has issued an emergency airworthiness directive (AD) for certain Airbus A220 aircraft, following the discovery of a potentially hazardous condition related to the aircraft’s Variable Frequency Generator (VFG) power-feeder harness. The directive, effective 25 August 2024, mandates immediate compliance to mitigate the risk of critical system failures.
The emergency AD, numbered CF-2024-29, applies to Airbus A220-100 and A220-300 aircraft with specific serial numbers. This follows reports of damage to the VFG power-feeder harness, which resulted in the loss of the generator and the activation of a L GEN FAIL caution message during flight. The issue was linked to a modification introduced by Airbus Canada in Service Bulletin (SB) BD500-534101, which aimed to prevent harness chafing by repositioning the cables. However, the modification inadvertently created new risks, leading to potential harness damage in different locations.
The AD specifically targets Airbus A220-100 (BD-500-1A10) and A220-300 (BD-500-1A11) aircraft with serial numbers 50010 through 50047 and 55003 through 55070, respectively. These aircraft had incorporated modifications under SB BD500-534101 at Issue 005 through Issue 008, which are now identified as potentially hazardous.
The VFG power-feeder harness is crucial for maintaining the electrical power supply within the aircraft. Chafing or damage to this harness could lead to the failure of both the primary and alternate power systems, resulting in the loss of critical aircraft systems. The risk is further exacerbated when certain items are inoperative under the Master Minimum Equipment List (MMEL), which the new directive now restricts.
Immediate Corrective Actions
To address these risks, the AD prohibits the dispatch of affected A220 aircraft under specific MMEL items related to the VFG, Auxiliary Power Unit (APU), and associated systems. The directive lists a series of MMEL items that are now restricted, including systems involving the VFG oil system, APU generator, and APU inlet door actuator.
Airlines operating the affected A220 aircraft are required to immediately comply with the AD, potentially grounding some aircraft until necessary inspections or modifications are completed. This emergency directive serves as an interim measure while further investigations are conducted. TCCA has indicated that additional airworthiness actions may be issued as more information becomes available.
Airbus Canada and operators of the A220 have been notified of the emergency directive and are expected to take immediate steps to ensure the continued airworthiness of the affected aircraft. Maintenance teams are urged to inspect the VFG power-feeder harnesses and address any identified issues to prevent further incidents.
