HEADQUARTERS OH-58A, Техническое руководство, Страница: 251 / 292

TM 55-1520-228-10
Figure 8-2. Effects of wind Azimuth On Aircraft.
(3) Disc vortex (280-330 degrees). Winds
within this region will cause the main rotor tip vortices
to be directed onto the tail rotor. The effect of this main
rotor vortex is to cause the tail rotor to operate in an
extremely turbulent environment. The helicopter will
exhibit a tendency to make a sudden uncommanded
right yaw whic
h,
if uncorrected, will develop into a spin.
When operating in this region, the pilot must anticipate
the sudden demand for left pedal inputs.
c. Other factors which may be present can signi fi -
cantly in fl uence the severity of the onset of Loss of Tail
Rotor Effectiveness (LTE). These factors are:
(1) Gross weight and density altitude. An in-
crease in either of these factors will decrease the power
margin between the maximum available and power re-
quired to hover. The pilot should conduct a low level,
low airspeed mission with only minimum essential per-
sonnel and equipment on board.
(2) Low indicated airspeed. At airspeeds below
ETL, the tail rotor is required to produce nearly 100 per-
cent of the directional control. If the required amount of
tail rotor thrust is not available, for whatever reason, the
aircraft will yaw to the right.
(3) Power droop. A rapid power application may
cause a transient power droop to occur. Any decrease in
main rotor RPM will cause a corresponding decrease in
tail rotor thrust. The pilot must anticipate this and apply
additional left pedal to counter the main rotor torque. All
power demands should be made as smoothly as possi-
ble to minimize the effect of the power droop.
Change 14 8-13