A Cityjet Canadair CRJ-900 on behalf of SAS Scandinavian Airlines, registration EI-GEC performing flight SK-2747 from Palanga (Lithuania) to Copenhagen (Denmark) with 69 passengers and 4 crew, was on approach to Copenhagen's runway 22L about 3-4 minutes before landing when the smell of smoke was observed on board followed by visible smoke. The flight crew donned their oxygen masks, declared Mayday, continued for a safe landing on runway 22L, vacated the runway and stopped on the taxiway, where passenger disembarked via the aircraft stairs.
Denmark's Havarikommissionen (HCL) rated the occurrence a serious incident and opened an investigation.
On Sep 3rd 2026 the HCL released their factual report summarizing the sequence of events:
On the approach to runway 22L the First Officer (FO) identified fumes (initially recognized as electrical). The Flight Commander (FC) could not smell any fumes.
Shortly after smoke was noticed from the side panel at the FC side.
The FC and the FO donned their full-face oxygen masks. They noticed that their vision through the visor of the oxygen masks was impaired. The visors were dusty and blurred.
Three to four minutes before landing, the flight crew declared an emergency (Mayday) and decided to continue the approach and land.
After landing, the aircraft vacated the runway, stopped on the taxiway and shut down both engines.
The smoke had evaporated and the FC and the FO removed their oxygen masks and noticed a L PACK AUTOFAIL caution displayed on the EICAS (Engine Indication and Crew Alerting System) display.
The fire brigade inspected the aircraft from the outside and could not see any sign of heat, smoke or fire.
The flight crew informed the cabin crew of the situation. The cabin crew informed that smoke had been visible in the forward part of the passenger cabin.
The passengers, the FO and the cabin crew disembarked the aircraft normally.
The fire brigade inspected the passenger cabin and flight deck and could not find any traces of heat or smoke.
After landing an onsite test revealed: "During the operational test of the air condition distribution system a rapid increasing ACU discharge temperature was observed with no airflow from the Left Hand (LH) ACU. The FIM suggested failure of the LH ACU ACM."
The HCL continued:
The ACM was shipped to the Original Equipment Manufacturer (OEM) for a tear down inspection.
An accredited representative from the BEA participated in the tear down inspection at the OEM on behalf of the AIB.
Findings:
- The compressor/turbine shaft could not be rotated.
- Compressor/turbine shaft thrust air bearing (turbine side) found completely damaged by friction and heat with signs of whitish deposit marks most probably from moisture ingress.
- Compressor/turbine shaft thrust air bearing (compressor side) found degraded by friction and heat.
-Turbine wheel had rubbed hard against the turbine shroud with damages to the turbine wheel and shroud.
- Eight Parts Manufacturer Approval (PMA) parts were found. Further testing of the PMA parts by the OEM, at an external laboratory, confirmed that six of the PMA parts did not comply to the OEM specifications relating to different material alloys, the mechanical properties and the manufacturing processes.
- General degradation of the ACM due to environmental conditions, including the accumulation of ingressed liquids (water, de-icing fluid), combined with normal wear.
- Missing warranty seal (for tracking of last repair shop).
- Non approved modifications and maintenance practices.
The teardown inspection of the ACM concluded that the thrust air bearings most probably failed due to accumulated moisture ingress over time through the air supply combined with general degradation of certain parts. The moisture degraded the load‑carrying capability of the thrust air bearing causing contact between the air bearing and stop, resulting in excessive axial movement of the compressor/turbine shaft. This axial movement caused the turbine wheel to contact the turbine shroud leading to seizure of the ACM rotating shaft.
The fumes and visible smoke in the flight compartment were most likely caused by the degradation of the thrust air bearings, and by the turbine wheel contact with the shroud.
The fumes and visible smoke would not develop any further after the ACM rotating shaft had seized.
Mitigation action by the OEM:
In 2016 the OEM introduced Service Bulletin SB GG670-95009-21-03. This SB introduced a modification, where the air for the air bearings was taken from the turbine inlet instead of the compressor outlet reducing the content of moisture in the air to the air bearings. The modification had not been embodied on this specific ACM at the time of the serious incident.
The OEM reported in the European Coordination Centre for Accident and Incident Reporting Systems (ECCAIRS) the use of PMA parts which did not meet the OEM specifications and the non-approved modifications and maintenance practices.
Denmark's Havarikommissionen (HCL) rated the occurrence a serious incident and opened an investigation.
On Sep 3rd 2026 the HCL released their factual report summarizing the sequence of events:
On the approach to runway 22L the First Officer (FO) identified fumes (initially recognized as electrical). The Flight Commander (FC) could not smell any fumes.
Shortly after smoke was noticed from the side panel at the FC side.
The FC and the FO donned their full-face oxygen masks. They noticed that their vision through the visor of the oxygen masks was impaired. The visors were dusty and blurred.
Three to four minutes before landing, the flight crew declared an emergency (Mayday) and decided to continue the approach and land.
After landing, the aircraft vacated the runway, stopped on the taxiway and shut down both engines.
The smoke had evaporated and the FC and the FO removed their oxygen masks and noticed a L PACK AUTOFAIL caution displayed on the EICAS (Engine Indication and Crew Alerting System) display.
The fire brigade inspected the aircraft from the outside and could not see any sign of heat, smoke or fire.
The flight crew informed the cabin crew of the situation. The cabin crew informed that smoke had been visible in the forward part of the passenger cabin.
The passengers, the FO and the cabin crew disembarked the aircraft normally.
The fire brigade inspected the passenger cabin and flight deck and could not find any traces of heat or smoke.
After landing an onsite test revealed: "During the operational test of the air condition distribution system a rapid increasing ACU discharge temperature was observed with no airflow from the Left Hand (LH) ACU. The FIM suggested failure of the LH ACU ACM."
The HCL continued:
The ACM was shipped to the Original Equipment Manufacturer (OEM) for a tear down inspection.
An accredited representative from the BEA participated in the tear down inspection at the OEM on behalf of the AIB.
Findings:
- The compressor/turbine shaft could not be rotated.
- Compressor/turbine shaft thrust air bearing (turbine side) found completely damaged by friction and heat with signs of whitish deposit marks most probably from moisture ingress.
- Compressor/turbine shaft thrust air bearing (compressor side) found degraded by friction and heat.
-Turbine wheel had rubbed hard against the turbine shroud with damages to the turbine wheel and shroud.
- Eight Parts Manufacturer Approval (PMA) parts were found. Further testing of the PMA parts by the OEM, at an external laboratory, confirmed that six of the PMA parts did not comply to the OEM specifications relating to different material alloys, the mechanical properties and the manufacturing processes.
- General degradation of the ACM due to environmental conditions, including the accumulation of ingressed liquids (water, de-icing fluid), combined with normal wear.
- Missing warranty seal (for tracking of last repair shop).
- Non approved modifications and maintenance practices.
The teardown inspection of the ACM concluded that the thrust air bearings most probably failed due to accumulated moisture ingress over time through the air supply combined with general degradation of certain parts. The moisture degraded the load‑carrying capability of the thrust air bearing causing contact between the air bearing and stop, resulting in excessive axial movement of the compressor/turbine shaft. This axial movement caused the turbine wheel to contact the turbine shroud leading to seizure of the ACM rotating shaft.
The fumes and visible smoke in the flight compartment were most likely caused by the degradation of the thrust air bearings, and by the turbine wheel contact with the shroud.
The fumes and visible smoke would not develop any further after the ACM rotating shaft had seized.
Mitigation action by the OEM:
In 2016 the OEM introduced Service Bulletin SB GG670-95009-21-03. This SB introduced a modification, where the air for the air bearings was taken from the turbine inlet instead of the compressor outlet reducing the content of moisture in the air to the air bearings. The modification had not been embodied on this specific ACM at the time of the serious incident.
The OEM reported in the European Coordination Centre for Accident and Incident Reporting Systems (ECCAIRS) the use of PMA parts which did not meet the OEM specifications and the non-approved modifications and maintenance practices.
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