Initial Models

R22		Initial model, first flight August 1975
R22HP		Faster, higher OGE
R22 Alpha		Higher gross weight, CG range is wider, higher tail rotor
R22 Beta		131 hp takeoff rating, higher capacity oil cooler, improved heater, larger instrument panel, new muffler design, elastic teeter-hinge stop

Safety Documentation

• National Transportation Safety Board Special Investigation Report
  Robinson Helicopter Company R22 Loss of Main Rotor Control Accidents
  Adopted April 2, 1996

• FAA record in Federal Register
  Robinson R-22 and R-44 Special Training and Experience Requirements
  November 21, 1997

• An analysis of R-22 accidents.