Accident Sikorsky S-76C+ OH-HCI, 10 Aug 2005
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ASN Wikibase Occurrence # 44382
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Type:Silhouette image of generic S76 model; specific model in this crash may look slightly different    
Sikorsky S-76C+
Registration: OH-HCI
MSN: 760508
Fatalities:Fatalities: 14 / Occupants: 14
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Location:Baltic Sea, off Tallinn -   Estonia
Phase: En route
Nature:Passenger - Scheduled
Departure airport:Tallinn heliport, Estonia
Destination airport:Helsinki/Hernesaari heliport, Finland
Confidence Rating: Accident investigation report completed and information captured
On August 10, 2005, at about 12:45 local time, a Copterline Sikorsky S-76 helicopter, registered in Finland as OH-HCI, crashed into the Baltic Sea shortly after takeoff from Tallinn, Estonia. The 2 crewmembers and 12 passengers onboard were fatally injured. The passengers were citizens from Finland, Estonia and the US.

The helicopter was destroyed by water impact. The wreckage was located in at a depth of 45 meters and at coordinates: North 59 degrees 32 minutes 546 seconds and East 24 degrees 43 minutes 852 seconds. Weather in the area of the accident was covered by the north-east part of a low pressure front. The winds were 110 degrees at 14 knots at the surface and at 1000 - 2000 feet the winds were at 130 degrees at 25 - 30 knots. The lowest cloud base was at 800 - 1400 feet. Temperature was 14 degrees Celsius and the dew point was 13 degrees Celsius.

The accident helicopter departed from Tallinn City Hall heliport at about 12:39 local time for a scheduled flight to Helsinki, Finland. The flight normally lasts 18 minutes and is about 80 kilometers in distance. The accident flight crew had already performed 5 landings at Tallinn City Hall heliport that day. The operator, at the time of the accident, operated 28 daily scheduled flights between Helsinki and Tallinn on weekdays. Shortly after takeoff, the flight had reached an altitude of 1500 feet and the flight crew began a climb to 2000 feet. The FDR data shows a change in collective position shortly before the helicopter pitches up abruptly and then rolls to the left. Witnesses saw the helicopter crash and an air traffic controller observed the helicopter disappear from radar coverage. As a result, a search and rescue operation was launched immediately.

The accident investigation is being conducted by the Government of Estonia as the state of occurrence. They have formed an Aircraft Accident Investigation Commission that is comprised of 8 individuals. There are accredited representatives from Finland, the United States (US) and France. The Safety Board sent an accredited representative and an airworthiness specialist to assist the Commission. Sikorsky and the Federal Aviation Administration also sent technical advisors. They were on-scene for over two weeks. Wreckage examination revealed that the floats had not been deployed and that the main rotor and tail rotor blades were intact until water impact. The engines were sent to the manufacturer in France for further examination. The recorders were downloaded at the recorder manufacturer in the United Kingdom. US manufactured parts that were part of the transmission and flight controls were sent to the US for examinations, testing and teardowns. As a result, Honeywell and HR Textron were added as technical advisors to the US.

The Estonian investigation commission released an interim report in August 2007 and a final report in August 2008.

The Aircraft Accident Investigation Commission determined that the cause of the accident was an uncommanded extension of the main rotor forward actuator and subsequent loss of control of the helicopter. Contributing to the uncommanded extension of the actuator was the separation of the plasma coating on one of two actuator pistons and the operator’s failure to detect the internal leakage of the main rotor forward actuator.

In the months following the accident, the Commission initiated interim safety recommendations, which resulted in NTSB Safety Recommendations A-05-33 through -35, Sikorsky All Operators Letter CCS-76-AOL-05-2001, FAA Special Airworthiness Information Bulletin SW-06-15, and an FAA Notice of Proposed Role Making (2006-SW-05 AD).

In this report, the Commission issued four additional safety recommendations addressed to Sikorsky, FAA, NTSB, Copterline and CAA-Finland.


Accident investigation:
Investigating agency: 
Status: Investigation completed
Download report: Final report
Safety recommendations:

Safety recommendation A-05-33 issued 17 November 2005 by NTSB to FAA
Safety recommendation A-05-34 issued 17 November 2005 by NTSB to FAA
Safety recommendation A-05-35 issued 17 November 2005 by NTSB to FAA
Safety recommendation A-06-17 issued 7 March 2006 by NTSB to FAA
Safety recommendation A-06-18 issued 7 March 2006 by NTSB to FAA


Photo: Scandinavian Observer

Photo: Scandinavian Observer

Revision history:

28-Oct-2008 00:45 ASN archive Added
01-May-2009 11:34 harro Updated
01-May-2009 12:05 slowkid Updated
01-May-2009 20:50 slowkid Updated
11-Jun-2010 11:59 TB Updated [Aircraft type, Cn, Location, Departure airport, Destination airport, Source, Narrative]
15-Aug-2015 13:21 Aerossurance Updated [Source, Narrative]
15-Aug-2015 13:29 Aerossurance Updated [Source]
08-Oct-2018 19:14 harro Updated [Photo]
08-Oct-2018 19:15 harro Updated [Photo, Accident report, ]

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