McDonnell Douglas Md-520n

Single Rotorcraft

The McDonnell Douglas MD 520N is a light utility helicopter distinguished by its revolutionary NOTAR (NO TAil Rotor) anti-torque system, which replaced the conventional tail rotor with a variable-pitch fan and directed thrust from the tail boom. Introduced in the early 1990s as an evolution of the Hughes 500 lineage, the MD 520N eliminated the most dangerous component of traditional helicopters—the exposed tail rotor—dramatically improving safety around ground personnel and reducing acoustic signature. The NOTAR system uses engine bleed air expelled through slots along the tail boom to generate anti-torque via the Coandă effect, making the aircraft quieter and less vulnerable to tail strikes or foreign object damage. Powered by a single Rolls-Royce 250-C20R turboshaft engine producing 375 shaft horsepower, the MD 520N seats five and serves law enforcement, emergency medical services, corporate transport, and utility roles worldwide. Its compact size, excellent visibility, and docile handling characteristics made it popular with police departments—the type became iconic in American law enforcement aviation during the 1990s and 2000s. Maximum cruise speed reaches approximately 122 knots, with a service ceiling around 16,000 feet and endurance of roughly 2.5 hours depending on configuration. The absence of a tail rotor also allows the aircraft to operate safely in confined areas where conventional helicopters would risk striking obstacles. Production continued under MD Helicopters after Boeing acquired McDonnell Douglas in 1997, with the type remaining in limited production into the 2000s before being succeeded by updated variants. While never produced in the thousands like piston trainers, the MD 520N carved out a loyal niche among operators prioritizing safety and stealth. SkyMeter has tracked 38 flights across 10 airframes and 8 operators over routes, with PRINCE GEORGES COUNTY POLICE DEPARTMENT the largest observed operator.