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MA State Police Airwing
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The Massachusetts State Police Air Wing is a unit within the Department of State Police, which specializes in support of ground police operations through the use of its aircraft. The unit currently consists of 5 helicopters: four twin engine American Eurocopter AS355N Twin Star models, and one single engine AS350 Astar. The single engine Astar is the oldest in the fleet, and is used primarily as a training copter for newer pilots and autorotation drills. Autorotation is not practiced in the twin-engine aircraft because it is not endorsed by the factory due to the extremely miniscule odds associated with simultaneous catastrophic failure of both engines. Autorotation is a condition where the main rotor is allowed to spin faster than the engine driving it. All helicopters are fitted with a free wheeling unit between the engine and the main rotor, usually in the transmission. The free wheeling unit will allow the engine to drive the rotors but not allow the rotors to turn the engine. When the engine/s fail the main rotor will still have a considerable amount of inertia and will still want to turn under its own force and through the aerodynamic force of the air through which it is flying. The free wheeling unit is designed in such a way to allow the main rotor to now rotate of its own free will regardless of engine speed. This principle is the same reason that if you are in your car and you push your clutch in, or put it into neutral while the car is still moving, the car will coast along under it's own force. This occurs regardless of what you do to the accelerator pedal. The pilot will still have complete control of his descent and his flight controls. The majority of helicopters are designed with a hydraulic pump mounted on the main transmission. As the rotor will still be turning the transmission, the pilot will still have hydraulically assisted flight controls. The pilot will be able to control his descent speed and main rotor RPM with his collective control stick. He will be able to control his main rotor RPM by increasing the collective pitch, which will increase drag on the rotor blades and thereby slow the main rotor. If he needs to increase his rotor RPM, he can decrease his collective pitch therefore decreasing drag. The pilot will usually be able to find a suitable area for a safe landing by normal manipulation of his cyclic control stick and his directional, or tail rotor pedals. Larger helicopters will usually have a generator mounted on the transmission that will still provide electrical power for flight and communication systems.
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