DAVID LEARMOUNT / LONDON
Loss of control is the most common cause of accidents involving French-registered Robinson R22 light helicopters, according to a study by French accident investigation agency BEA. The study was carried out because of the R22's popularity with limited-experience pilot-owners and flying schools, and has analysed the kind of accidents the type most often suffers.
The report reminds operators that the low inertia of its rotor makes the aircraft vulnerable, and is a factor in "numerous accidents in France and around the world", but makes it clear that the statement is addressing a fact rather than a fault. It advises that sudden control movements are prone to induce excessive blade flapping, and that the piston engine has limited reserve power during transitional flight, and in hot or high conditions.
Loss of control is the cause of nearly half of the R22 accidents in France. Mechanical problems, collision with obstacles and accidents during training are also common. The study's advice to pilots includes:
Cruise above 500ft (150m); maintain 60kt (111km/h) minimum in the climb and cruise; follow the flight manual advice about safe heights for hovering and transitional flight; increase power or lower the collective control at the onset of rotor RPM decay; during autorotation training, apply power at 500ft above ground level if autorotative descent goes outside standard parameters, which means minimum airspeed 65kt and rotor rpm in the green sector; no sudden control movements; ensure flight at altitude leaves sufficient reserve power.Source: Flight International
