TALLINN - The victims of the 2005 Copterline helicopter crash endured 37 seconds of terror as the aircraft spun 13 times mid-air before plunging 500 meters into the sea, killing all on board.
New details of the crash were revealed by the Estonian government's investigating commission, which released an interim report in Tallinn on Aug. 8.
The report outlined the final moments aboard the Sikorsky S-76 aircraft, which crashed into the Bay of Tallinn only three minutes after departing en route to Helsinki.
Members of the commission listened to pilot voice recordings from inside the helicopter that were recovered from the aircraft's "black box" data recorder.
"There was nothing dramatic, no exclamations," said Tonis Ader, vice chairman of the public commission set up by the Ministry of Economic Affairs and Communications to identify the cause of the accident.
"Most of their phrases are in the report 's there is nothing to hide. It was quite a strange event that covered a short period of time."
The commission handed down its interim report almost two years to the day since the crash that claimed fourteen lives. The report confirmed previous speculation that a fault in the helicopter's main rotor servo caused the accident, and rules out earlier theories that either pilot error or freak weather conditions, such as a water spout, were to blame.
Tests conducted on the wreckage found that flakes of plasma coating on an internal piston caused a fluid blockage that led to the failure of the servo. The coating was found to be too thick by a matter of fractions of a millimetre, a minor fault with major implications.
The helicopter was thrown into an uncontrollable spin, making 13 full rotations before it hit the water 500 meters below.
"There was tremendous acceleration inside the helicopter, which made the actions of the pilots very difficult," Ader said. "This is the most probable cause as to why the pilots did not activate emergency flotation systems."
Further issues were found with the emergency flotation system, which is supposed to deploy large airbags. The system was switched off, a common procedure to avoid unintentional deployment upon take-off.
Copterline, the Finnish-based operator of the flight, said the interim report vindicated its pilots and maintenance crew.
Copterline managing director Kari Ljungberg said the error lay in the design and construction of the servo, and could not have been foreseen.
He said the company had since learned that the servos were second-hand and 25 years old. "If we had known they were recycled parts we would never have bought themâ€¦ This has hurt our business because although we have known the cause of the accident was not our fault since 2005, we have been unable to say it publicly," Ljungberg said.
Copterline no longer flies between Tallinn and Helsinki, and Ljungberg said the company would decide in a matter of weeks whether to reopen the route.
Meanwhile, the Sikorsky helicopter manufacturing firm has admitted to paying compensation to the families of the victims 's the first acknowledgement of blame since the crash.
Sikorsky told the Finnish newspaper Helsingin Sanomat that an agreement had been reached with victims' families, but refused to reveal the amount.
Two lawsuits remain lodged with courts in New York. Copterline and the families of the pilots are seeking damages from Sikorsky and Textron, the vendor of the faulty part, and Plasma Technology, another company involved in manufacturing the part.
The commission said it would hand down its final report in a matter of months.