Confined site with various small buildings in the immediate vicinity. As the helicopter lifted off, it yawed to the left butÂ the pilot over corrected. He then applied more collective in an attempt to escape from the situation but the helicopter yawed through about 180Â° and reached a height of about 25 to 30 ft, before descending. Before hitting the ground, the pilot pulled the cyclic control aft, to slow down. The tail struck the ground and the main rotor blades struck a nearby Portakabin, causing it severe damage. The helicopter came to rest upright on its skids. The pilot, who had not flown in the preceding 90 days, attributed the accident to over controlling on pedals and collective.