PARTS AND MAINTENANCE

The enclosed variable-pitch composite blade fan produces a low-pressure, high volume of ambient air to pressurize the composite tail boom. 

The air is expelled through two slots that run the length of the tail boom on the starboard (right) side, causing a boundary-layer control called the Coanda Effect. The result is that the tail boom becomes a “wing,” flying in the downwash of the rotor system, producing up to 60 percent of the anti-torque required in a hover. The balance of the directional control is accomplished by a rotating direct jet thruster. In forward flight, the vertical stabilizers provide the majority of the anti-torque. However, directional control remains a function of the direct jet thruster. 

There are two production helicopters that utilize the NOTAR system, both produced by MD Helicopters.

• Greater Safety: Studies have shown that 21% of all crashes are due to tail rotor strikes or loss of tail rotor effectiveness. NOTAR® systems eliminate these problems.
• Reduced Noise: Designed and tested to be 50% quieter, NOTAR-equipped helicopters are among the quietest certified helicopters available.
• Reduced Pilot Workload: Using the Coanda Effect to provide tail boom lift and anti-torque, the system is more stable and easier to control. This effect reduces the sensitivity to wind direction on helicopter control.
• Reduced Aircraft Vibration: The inherent stability of the standard MD 500 is further improved by the elimination of the exposed tail rotor assembly, which reduces overall helicopter vibrations and increases passenger comfort while reducing pilot fatigue.