Limited Power Operations For Helicopters

1. Power Check for Landing The power check should be carried out at a safe altitude above the intended landing area. Fly the helicopter straight and level at forty knots of airspeed (Forty knots of airspeed is where the helicopter uses the least amount of power.) and note the manifold pressure. Maximum power is now applied while straight and level flight is maintained. The difference between these two figures is the power margin available. Less than 2" of manifold pressure available would mean a run on landing is necessary. 2"- 4" of manifold pressure available would mean a zero speed landing is possible 5" of manifold pressure available would mean a two foot hover is possible 6" of manifold pressure available would mean a four foot hover is possible 7"- 8" of manifold pressure available would mean a steep approach to a four foot hover is possible. During the approach the decision has to be made whether to complete the approach or abort and go around. 2" of reserve power should be kept in hand and translational lift maintained until you have reached your decision point. The decision point will depend on obstructions on the approach and departure paths, wind, turbulence and nature of the landing area.

2. Power Check for Takeoff Hold the helicopter in a two foot hover and note the manifold pressure. The difference between the maximum obtainable manifold pressure and the power during the hover is the power margin available. Less than 1" manifold pressure means that a running takeoff is necessary. 1" - 2" of manifold pressure available means that a creeping takeoff is possible. 2" - 3" of manifold pressure available means that a towering takeoff is possible. 5" of manifold pressure available means that a vertical takeoff and out of ground effect hover is possible. Common errors when operating with limited power. Over controlling. Poor Rotor rpm control. Failure to maintain correct rate of descent. Failure to decide to go around. Selecting the wrong type of approach or departure. Over controlling uses more power. Use smooth control inputs while attempting operations with limited power.