07 August 2019 Wednesday
Common causes of helicopter accidents
IGU Aircraft Engineer Prof. Osman Ergüven Vatandaş named a number of reasons which can increase the rist of helicopter crash .High-tension lines, trees, buildings and poles are among them. Moreover, vertical position in the air, hanging in the air, taking off and landing in difficult areas are said to affect search rescue and medical intervention procedures.
Prof. Osman Ergüven Vatandaş, who is a lecturer of istanbul Gelisim University School of Applied Sciences, commented on the technical features of helicopters and the accident causes .
Mentioning that helicopters are more affected by meteorological changes at low altitude, Prof. Vatandaş said: “High-tension lines, trees, buildings and poles etc on the ground can pose crash hazard to helicopters”.
COMMON CAUSES OF HELICOPTER ACCIDENTS
Prof. Dr. Vatandaş told about the main reasons for helicopter crashes: ”The causes can be grouped in some main categories. Operational errors ( e.g. mistakes in operational or maintenance procedures), mechanical and electrical malfunctions and some external factors. Engine breakdown, tail- rotor failure, low visibility distance caused by bad weather conditions, flight at a low altitude and pilot mistakes can cause accidents as well”.
AUTOROTATION PILOTAGE METHOD
Prof. Vatandaş talked about ‘autorotation’ method, which is used in case of engine failure. “ Pilots are tought and made to implement this method regularly. This method resembles percolation. At the instant of engine sailure, the main rotor blades are producing lift and thrust from their angle of attack and velocity. By immediately lowing the collective pitch the pilot reduces lift and drag and the helicopter begins an immediate descent. Moreover, it should be mentioned that the crash rate of helicopters are higher comparing to the planes” said Prof. Vatandaş.
MEASURES TO BE TAKEN
Prof. Osman Ergüven Vatandaş emphasized the high level of education for military pilots in Turkey. “ As an example I can mention the operation held in Diyarbakir when a helicopter descended over Dicle river and staying hanged in the air allowed to save all the people on the board. The team which conducted this operation was considered worthy bravery and competence award by Sikorsky company. The existence of rotating systems in helicopters can create a risk of mechanic and hydraulics systems failure. Moreover, such barriers as high voltage lines etc can be a cause of helicopter accidents. As a measure for it wire sawa are attached to helicopters. Usually the are attached to the bottom and top of a helicopter. When a helicopter faces an obstacle of high tension wire the saws cut the wires. Moreover, to decrease this risk it is necessary to mark high voltage wires with plastic objects and lights” he said.
