User Guide

Two steps are essential to accomplish this. In the first place, as soon as the engine thrust

disappears you must instantly bottom the collective, which reduces the main rotor pitch

angle to its lowest value and minimizes the drag on the rotor blades. At the same time, if

you have the height and space to maneuver, you should try to preserve the helicopter’s

forward motion and minimize the rate of descent by using the cyclic to trim your speed to

the minimum-rate-of-descent figure – about 70-80 knots/130-150 kmh. The resulting airflow

will actually drive the main rotor around, just as it does in an autogyro (which has a powered

propeller to give it forward speed, which drives its unpowered rotor). This is what the word

Autorotation means. It is to a helicopter what gliding flight is to a fixed-

wing aircraft.

Unfortunately, a heavy combat helicopter glides about as well as a fast jet does. Because

of the low speeds involved, and the rotor’s ability to deliver braking thrust straight down, it

is still possible to land safely, but a very steep descent may be required to keep the main

rotor turning. Your pull-out/round-out maneuver must be finely judged to avoid either hitting

the ground in the dive or finding yourself running out of airspeed and rotor rpm with the

ground still an uncomfortable distance below.

At the same time as the collective is bottomed and the cyclic trimmed, the pilot must also

scan the area below and ahead (and preferably upwind) for the best place to put down and

steer towards it. There is no time for hesitation or indecision in this sequence unless you

have a great deal of height to spare. Action and decision must be nearly instantaneous, and

once you’ve made your choice of landing area you are committed.

2) Loss of Power at Low Level

This is a more likely scenario for an attack helicopter than the classic autorotation described

above. Your options are essentially limited to flaring more or less straight ahead, and/or

raising the collective to convert rotational energy into braking thrust before you hit the

ground. The helicopter will probably take severe damage, but its structure is designed to

absorb energy and protect the crew in precisely this situation. Combat helicopter crews can

expect to survive crashes which would be instantly fatal in most kinds of aircraft.

GROUND SCHOOL