C7/2004L Helicopter accident in Naruska in the community of Salla on 16 October 2004

A flight accident occurred involving a Robinson R22 Mariner-type helicopter (registration sign OH-HTE), owned by Helitour Oy, approximately 14 km north of the village Naruska in the community of Salla on Saturday October 16th 2004 at 16:55 Finnish time, when the helicopter’s engine lost power during a reindeer management flight and the pilot made a forced landing into the forest. The helicopter had a two-man crew. Neither crewmember was injured in connection with the forced landing. The helicopter was significantly damaged in the forced landing. The Accident Investigation Board Finland commenced an official investigation of the event, nominating investigator Ari Huhtala as chairman and investigator Timo Rantala as team member. Investigator Juhani Mäkelä assisted in the investigation.

The helicopter was hovering low at an altitude of about 50 meters and began to move turning simultaneously to the right. Suddenly a bang was heard and the low-RPM warning alert was activated at the same time. The helicopter’s engine had failed and the helicopter began to lose altitude continuing the turn to the right. About ten meters before ground contact the rotor blades struck trees and were broken, after which the helicopter was no longer controllable.

The distributor wheel on one of the helicopter magnetos was broken during the flight and adjusted the ignition timing earlier so that the engine stopped. Due to the low flight altitude and speed the forced landing to the terrain failed.

The investigators recommended, that the Finnish Flight Safety Authority should require that the condition of the distributor gear teeth on TCM (Teledyne Continental Motors, formerly Bendix) magnetos in use on helicopters always to be checked in connection with 100-hour service inspections. The investigators further recommended that in field conditions the flight operator should properly transport and the store the fuel intended for aircraft use, as well as use a chamois or equivalent filter when refuelling aircraft in such conditions. In addition, the flight operators should encourage the pilots to report about backfiring cases at engine start up.

A statement regarding the investigation report was requested from the Finnish Flight Safety Authority, Helitour Oy, and Helitech Oy. The statements have been taken into account in the investigation report.

C7/2004L Report (pdf, 0.69 Mt)