Serious incident Eurocopter EC-145 LN-OOS,
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ASN Wikibase Occurrence # 278558
 
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Date:Saturday 20 November 2021
Time:19:09 loc
Type:Silhouette image of generic EC45 model; specific model in this crash may look slightly different    
Eurocopter EC-145
Owner/operator:Norsk Luftambulanse
Registration: LN-OOS
MSN: 20039
Fatalities:Fatalities: 0 / Occupants: 3
Aircraft damage: Substantial
Category:Serious incident
Location:Kongsvikdalen, Lofoten -   Norway
Phase: En route
Nature:Ambulance
Departure airport:
Destination airport:
Investigating agency: NSIA
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The EC-145 helicopter, operated by Norsk Luftambulanse AS, was on a search and rescue mission in the Kongsvikdalen valley in Lofoten. It was dark and there were snow showers in the area. The helicopter operated in snow of varying intensity while the crew waited for the party in distress to arrive at the landing site. Icing conditions were not forecast, and snow is not automatically defined as icing conditions.
An assessment of the weather conditions must be made to determine if icing is suspected or not. It took longer than the crew anticipated for the party in distress to reach the helicopter. During this period the helicopter operated in hover and on the ground with the engines running. After the party in distress boarded, the helicopter flew east and south-east towards Kongsvika.
The crew were aware of a power line that crosses Kongsvikdalen valley, but they had not located it visually. Therefore, they flew slowly down the valley while they searched. Suddenly, and without warning, the left engine shut down. The crew made an emergency landing without issue and without anyone being injured. While the helicopter was on the ground, the right engine also suddenly shut down.

The Norwegian Safety Investigation Authority believes that both engines on LN-OOS shut down due to flameout caused by the ingestion of ice. The investigation and tests after the incident have not found any technical fault with the engines that could have caused the shutdowns. The ice probably built up in the Inlet Barrier Filter (IBF) system while the helicopter was waiting for the party in distress. The IBF system is a dust and particle filter that replaces the standard air inlet.

Flight tests by Airbus Helicopters Deutschland after the incident have shown that, under certain weather conditions, significant amounts of ice can build up in the IBF system and this ice can enter the engine unhindered. The weather conditions that can cause ice build-up are typical Norwegian winter conditions along the coast with temperatures of around zero degrees centigrade and high humidity.

Accident investigation:
cover
  
Investigating agency: NSIA
Report number: 
Status: Investigation completed
Duration: 12 months
Download report: Final report

Sources:

AIBN


Revision history:

Date/timeContributorUpdates
31-May-2022 18:38 Medevac Added
31-May-2022 18:39 harro Updated [Aircraft type, Total occupants]
16-Nov-2022 13:12 harro Updated [Registration, Cn, Operator, Total occupants, Location, Source, Narrative, Category, Accident report]

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