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Turn Indicator
During coordinated flight, the needle of the turn-and-slip
indicator gives an indirect indication of the bank attitude
of the helicopter. When the needle is displaced from the
vertical position, the helicopter is turning in the direction of
the displacement. Thus, if the needle is displaced to the left,
the helicopter is turning left. Bringing the needle back to
the vertical position with the cyclic produces straight flight.
A close observation of the needle is necessary to accurately
interpret small deviations from the desired position.
Cross-check the ball of the turn-and-slip indicator to determine
if the helicopter is in coordinated flight. [Figure 6-6] If
the rotor is laterally level and pedal pressure properly
compensates for torque, the ball remains in the center. To
center the ball, level the helicopter laterally by reference to
the other bank instruments, then center the ball with pedal
trim. Torque correction pressures vary as power changes are
made. Always check the ball after such changes.
Common Errors During Straight-and-Level Flight
1. Failure to maintain altitude
2. Failure to maintain heading
3. Overcontrolling pitch and bank during corrections
4. Failure to maintain proper pedal trim
5. Failure to cross-check all available instruments
Power Control During Straight-and-Level Flight
Establishing specific power settings is accomplished through
collective pitch adjustments and throttle control, where
necessary. For reciprocating-powered helicopters, power
indication is observed on the manifold pressure gauge.
For turbine-powered helicopters, power is observed on the
torque gauge. (Although most Instrument Flight Rules (IFR)-
certified helicopters are turbine powered, depictions within
this chapter use a reciprocating-powered helicopter as this
is where training is most likely conducted.)
At any given airspeed, a specific power setting determines
whether the helicopter is in level flight, in a climb, or in a
descent. For example, cruising airspeed maintained with
cruising power results in level flight. If a pilot increases the
power setting and holds the airspeed constant, the helicopter
climbs. Conversely, if the pilot decreases power and holds
the airspeed constant, the helicopter descends.
6-8
3
4
I
2
I 2
3
VERTICAL SPEED
THOUSAND FT PER MIN
UP
DOWN
.5
.5
0
33
30
24
2I
I5
I2
6
3
2 MIN TURN
DC ELEC
L R
30.0
29.9
29.8
I00
FE ET
I
6 5 4
7
9
2
0
8
3
CALIBRATED
TO
20,000 FEET
ALT R
O
F20 20
I0 I0
I0 I0
20 20
TEST STBY PWR
IN Hg
ALg.
MANIFOLD
PRESS
25
5
15
30
20
10
35
D
110
100
90
80
70
60
50
110
100
90
80
70
60
50
E R
%RPM
6-7a Flight instrument indications in straight-and-level flight with power increasing.
Figure 6-7. Flight instrument indications in straight-and-level flight with power increasing.
If the altitude is held constant, power determines the airspeed.
For example, at a constant altitude, cruising power results
in cruising airspeed. Any deviation from the cruising power
setting results in a change of airspeed. When power is added
to increase airspeed, the nose of the helicopter pitches up and
yaws to the right in a helicopter with a counterclockwise main
rotor blade rotation. [Figure 6-7] When power is reduced to
decrease airspeed, the nose pitches down and yaws to the
left. [Figure 6-8] The yawing effect is most pronounced in
single-rotor helicopters, and is absent in helicopters with
counter-rotating rotors. To counteract the yawing tendency
of the helicopter, apply pedal trim during power changes.
To maintain a constant altitude and airspeed in level flight,
coordinate pitch attitude and power control. The relationship
between altitude and airspeed determines the need for a
change in power and/or pitch attitude. If the altitude is
constant and the airspeed is high or low, change the power to
obtain the desired airspeed. During the change in power, make
an accurate interpretation of the altimeter, then counteract
any deviation from the desired altitude by an appropriate
change of pitch attitude. If the altitude is low and the airspeed
is high, or vice versa, a change in pitch attitude alone may
return the helicopter to the proper altitude and airspeed. If
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本文链接地址：
Instrument Flying Handbook仪表飞行手册上(121)
