Rotorcraft valuation service HeliValues has observed several recent trends in the rotorcraft market. The company, which publishes The Official Helicopter Blue Book, noted an increasing supply of light single-engine helicopters available on the world market, particularly the AS350 series, while due to the decline of the corporate and VIP markets and the introduction of more efficient light twins it has seen increasing numbers of older helicopters such as the AW109 enter the used marketplace. Despite concerns over the oil industry, the company said there continues to be strong demand for medium and heavy offshore-configured rotorcraft, while prices for their VIP/corporate outfitted siblings remain discounted.