B4/2005L Helikopterionnettomuus Tallinnan edustalla 10.8.2005

Copterline Oy:n omistamalle Sikorsky S-76 helikopterille 10.8.2005 Tallinnanlahdella tapahtunutta onnettomuutta tutkinut Viron liikenneministeriön tutkintakomissio julkisti tutkintaselostuksen 11.8.2008.

Tutkintaselostus on Onnettomuustutkintakeskuksen verkkosivuilla toistaiseksi vain englanninkielisenä. Suomenkielinen versio tutkintaselostuksesta julkaistaan myöhemmin.

Kansainvälisen siviili-ilmailun yleissopimuksen liitteen 13 mukaisesti nimettynä Suomen valtuutettuna edustajana onnettomuuden tutkintaan osallistui ilmailuonnettomuuksien erikoistutkija Hannu Melaranta Onnettomuustutkintakeskuksesta. Melarannan neuvonantajina toimivat yliluutnantti Timo Lindholm ja kapteeni Ari Anttila Rajavartiolaitoksen Turun vartiolentueesta sekä lentotekniikan diplomi-insinööri Markku Roschier.

SUMMARY

On 10 August 2005, a Sikorsky S-76C+ helicopter, registration OH–HCI, was operating a scheduled passenger service by Copterline between Helsinki, Finland and Tallinn, Estonia. The helicopter departed Tallinn at 12:39 hours (local time) with 12 passengers and two pilots on board. Approximately three minutes after take-off while climbing at 1380 ft above sea level, the flight data recorder showed that the flight was interrupted by a sudden helicopter pitch-up and left roll maneuver, then remained in varying attitudes of right yaw (rotation), roll and pitch for 37 seconds until impacting the water at 12:42:28 hours. There were no survivors.

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.

B4/2005L Tutkintaselostus (pdf, 2.75 Mt)