EASA Mandates APU Flap Inspections on Airbus A350 After In-Service Incidents

The European Union Aviation Safety Agency (EASA) has issued a new airworthiness directive requiring inspections of Airbus A350 auxiliary power unit (APU) air intake flaps after two in-service incidents revealed a recurring mechanical issue.

According to EASA’s Dec. 2 directive, Airbus reported two cases over the past two years in which A350 APU air intake flaps detached during operation. Investigations found cracked hinges caused by corrosion pitting, prompting deeper analysis into the factors that accelerate fatigue.

Further review showed that stress on the hinge assembly increases when an aircraft operates under approved master minimum equipment list (MMEL) conditions with the APU air intake flap left open while the APU is shut down. This configuration, though permitted, may contribute to cracking over time.

Honeywell, the APU supplier, issued a service bulletin in October outlining a new inspection program to detect and address the issue. Airbus followed with its own customer bulletin recommending immediate adherence to Honeywell’s checks and has since updated the A350 MMEL to reduce operational risk.

EASA’s directive formally mandates these actions. Operators must perform an initial inspection of the APU air intake flaps within 4–12 months, depending on aircraft usage and configuration. Recurrent inspections will then be required every 24 months. The directive also obliges airlines to adopt the revised MMEL procedures.

The new requirements aim to prevent further hinge failures and ensure continued safe operation of the A350 fleet.

By late 2025, there are about 682 Airbus A350s in service worldwide, operated by 39 airlines. The A350 family has become Airbus’s flagship widebody, with strong adoption across Asia, Europe, and the Middle East. Singapore Airlines leads with the largest active fleet at 65 aircraft, while carriers like Emirates, Delta, and Swiss International (SWISS) have recently expanded their A350 operations. This steady growth highlights the aircraft’s role as one of the most efficient and modern long‑haul jets in global service

Sources: AirGuide Business airguide.info, bing.com, aviationweek.com, airbus.com