On 5 May 2025, an Aer Lingus UK Airbus A330-300 operating transatlantic flight EG935 from Manchester to Orlando was forced to divert and return to Ireland following technical issues with its right-hand engine. The crew declared a PAN-PAN emergency and executed a precautionary overweight landing at Shannon Airport (SNN). Emergency services inspected the brakes and aircraft systems post-landing. The aircraft remained grounded for inspection as of six hours after touchdown.
This report provides a technical and procedural breakdown of the event, including operational decisions, aircraft systems, and risk mitigation measures.
Flight Overview
Operator: Aer Lingus UK Flight Number: EG935 Date: 5 May 2025 Aircraft Type: Airbus A330-302 Registration: G-EILA Engines: 2 × General Electric CF6-80E1A4 Departure Airport: Manchester (EGCC/MAN), United Kingdom Destination Airport: Orlando International (KMCO/MCO), United States Occupants: 304 (passengers and crew) Incident Location: 460 NM southwest of Shannon FIR, over North Atlantic Track Declared Emergency: PAN-PAN Diversion Airport: Shannon International Airport (EINN/SNN), Ireland Landing Runway: 06 Final Outcome: Safe overweight landing, full emergency brake inspection
Sequence of Events
Cruise and Initial Problem Detection
Flight EG935 had been airborne for approximately 1 hour 40 minutes and was cruising at FL330 over the North Atlantic Ocean, roughly 460 nautical miles southwest of Shannon. At this point, the flight crew identified a technical issue affecting the No. 2 (right-hand) engine, a General Electric CF6-80E1A4 turbofan.
While the precise nature of the fault was not publicly disclosed, symptoms may have included:
Abnormal engine vibration (ENG VIB) Oil pressure or temperature anomalies N2/N1 instability EGT exceedances Fuel control irregularities Autothrottle disengagement on affected engine
Upon confirming the issue through ECAM alerts and engine parameter monitoring, the crew elected not to shut the engine down, but to declare a PAN-PAN emergency, indicating an urgent but non-life-threatening technical condition.
Decision to Return and PAN Declaration
The declaration of PAN-PAN would have been made to the relevant Shanwick Oceanic and Shannon FIR controllers, advising of degraded engine performance and intent to divert.
A return to Manchester was not feasible due to distance, so Shannon (EINN) was selected as the nearest suitable diversionary airport with CAT III capability, extended runways, and full emergency support services.
System and Procedural Management In-Flight
The crew would have followed Airbus A330 QRH/ECAM abnormal procedures for engine degradation, including:
Monitoring vibration levels via built-in vibration sensors Cross-checking oil pressure, oil quantity, and oil temperature Examining EGT trends for signs of compressor or turbine instability If within tolerances, continued operation at reduced thrust to prevent further escalation Auto-thrust disconnection for affected engine if necessary Continuous monitoring of FADEC-controlled engine parameters
Since no engine shutdown occurred, it is likely that the engine retained thrust capability but with performance or reliability degradation that warranted a conservative return.
Approach and Overweight Landing
A330 aircraft are certified to land overweight under emergency conditions. The maximum landing weight (MLW) for the A330-300 is typically around 187,000 kg, while maximum takeoff weight (MTOW) is approximately 242,000 kg.
In this event, the crew did not conduct a fuel dump (not available on all A330 variants), opting to land at an estimated overweight condition, likely 10–20 tonnes above MLW.
The ECAM overweight landing checklist would have been initiated, including:
Brake energy monitoring VAPP increase for landing configuration Use of maximum reverse thrust on the unaffected engine Configuring for full flap and autobrake MAX if required Communicating to ATC and emergency services that brakes and gear temperatures must be inspected post-landing
Landing Execution and Emergency Response
The aircraft landed on runway 06 at Shannon under stable meteorological conditions. The approach was flown manually or via autopilot with caution applied to:
Asymmetric engine thrust vectoring Landing distance computations with overweight margins Directional control in reverse thrust using only one engine
After touchdown, the aircraft rolled out and came to a complete stop at the end of the runway as previously coordinated with ATC. Emergency vehicles performed an external visual inspection, with particular focus on:
Main landing gear brake assemblies Tire condition Brake temperature sensors Hydraulic lines and heat signatures Gear door integrity
Once brake temperatures stabilised and no visible damage was confirmed, the aircraft was cleared for tow to a remote stand or taxi to an apron for further maintenance action.
Engine Type and Known Issue Considerations
CF6-80E1A4 Engine
The GE CF6-80E1 series powers the A330 family and has a strong service record, but is subject to known wear patterns in:
Fan blade dovetail wear Nozzle guide vane cracking LPT seal deterioration Fuel control unit (FCU) anomalies Oil system thermal sensor irregularities
In recent years, various operators have reported vibration-related returns due to uncommanded engine stall margin shifts, which are typically recoverable but require immediate ground inspection.
It is possible that the issue encountered on EG935 involved one or more of these degradation patterns, though no final diagnosis has yet been issued.
Aircraft Technical Profile
Aircraft: Airbus A330-302 Registration: G-EILA Age: Approx. 10–14 years Configuration: Long-haul economy and premium Engines: 2 × GE CF6-80E1A4 Certification: ETOPS-180 compliant Maintenance Authority: UK CAA, Aer Lingus CAMO
As of 6 hours post-landing, G-EILA remains grounded at Shannon, undergoing diagnostics on the No. 2 engine and landing gear components. Return-to-service is subject to:
Borescope inspection of the engine FADEC data download and trend analysis Brake unit thermal profile assessment Possible engine run-up and test cell certification
Passenger Handling and Operational Recovery
Passengers were disembarked normally after the aircraft was cleared and towed to a remote stand. Aer Lingus UK coordinated passenger rebooking through connecting services from Shannon or ground transportation to Dublin.
Passengers were advised that the precautionary diversion was due to a technical irregularity and no unsafe conditions occurred during flight or landing.
The flight was officially cancelled, and luggage was offloaded for re-routing.
Conclusion
The Aer Lingus UK flight EG935 diversion on 5 May 2025 demonstrates standard but effective application of abnormal procedures and engine failure risk management. While no engine shutdown occurred, the crew’s declaration of PAN-PAN and overweight landing request reflect strong adherence to manufacturer and regulatory guidance.
The absence of injuries and the calm, controlled resolution reinforce the value of early problem identification and decisive command actions in oceanic ETOPS operations. The A330’s systems and Shannon’s infrastructure supported a safe outcome.
Pending full engine diagnostics and inspection reports, G-EILA will remain out of service. No further issues have been reported across the airline’s A330 fleet.
Disclaimer
This article is based on publicly available information and reports at the time of writing. While every effort has been made to ensure accuracy, we cannot guarantee the completeness of the information provided.
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