including sabotage and collision with a flock of birds. As the helicopter was manufactured in the United States, the U.S. National Transportation Safety Board (NTSB) has taken part in the investigation. In November 2005, the NTSB issued an "urgent" recommendation to the FAA to require all S-76 operators to carry out "immediate visual and laboratory examinations" of main rotor servos for plasma flakes and other contamination. The helicopter manufacturer, Sikorsky Aircraft, rejected these findings, saying it and servo manufacturer HR Textron "do not agree that the servo caused the mishap". In December 2005 the company, however, issued an all-operators letter recommending that operators carry out internal leakage tests of all S-76 main rotor servos, at the same time emphasizing that testing with an intentionally degraded servo "has not identified any safety of flight issues". The talks between Copterline and Sikorsky Aircraft about how to divide damages arising from the crash broke down in December 2006, and Copterline sued Sikorsky Aircraft in a U.S. court in New York for damages of 60 million US dollars. In August 2007 it was announced that the cause of the crash was a failure of the hydraulic flight control system, caused by coating flaking off from servo pistons. The loosened plasma coating flakes blocked the return valves of the servos, causing the aircraft to abruptly lose its maneuverability. Copterline did not have the authority to service or even open these components. However, in the final report, Copterline was criticized for omitting a periodic leak test of the hydraulic flight control system that could have revealed the problem. The Finnish authorities were also criticized for insufficient supervision. References Lennuõnnetus Copterline OY helikopteriga Sikorsky S76 C+ Registritähis OH – HCI Tallinna lahel, 10. augustil 2005 6. august 2008 Tõlge (accident report) - On the website of the Estonian Safety Investigation Bureau (ESIB). Profile. - Also see: Document on the ESIB website (Profile) and .doc version of this report at the ministry website. Preliminary accident report on the ESIB website. Profile. Press releases: Estonian Ministry of Economic Affairs and Communications (2006-02-15). "The helicopter accident investigation commission got together today." Press release. External links 2005 disasters in Europe Aviation accidents and incidents in Estonia Aviation accidents and incidents in Finland Aviation accidents and incidents in 2005 Accidents and incidents involving the Sikorsky S-76 2005 in Estonia 2005 in Finland August 2005 events in Europe