Being a police pilot, guess I'd like to comment on this a little.
First off, for most police departments on the other side of the pond, they do not "patrol" with their helicopters. They do not fly as often, or cover the area that some do over here. An example being, that my department covers 4,000+ sq. miles of area. The only way to provide service is to have as many ships out as possible. Economics dictate singles due to this. We poactively are out looking for "crime" and assisting the ground units. During a shift we average a total of 5 hours in the air.
Our fleet puts on about 10,000 hours a year, 99% of it in singles. The only engine failure in a turbine was about 12 years ago, and the pilot knew the engine had problems, but kept flying it (for several days prior, he admitted it was having compressor stalls) until it quit. We operate from sea level to 9,000 feet with temps from below zero to 40c+. Lots of IGE and OGE hovers also due to search and rescues. Pretty good record for a single.
I would love to have a twin, but statistics just do not prove it out in my job. And as far as smaller streets, in the city here, it will not be any better doing an auto onto the street.
And our training ship (MD500D) that we practice all of our full touch down auto's has 17,000 hours.
