IN Hg ALg. MANIFOLD  PRESS  25 5 15 30 20 10 35 110  100  90  80  70  60  50  110  100  90  80  70  60  50  E R  %RPM  3  4  I  0  2  2  I  3  VERTICAL SPEED  THOUSAND FT PER MIN  UP  DOWN  .5  .5  33  30  24  2I  I5  I2  6  3  2 MIN TURN  DC ELEC  L R  30.0  29.9  29.8  I 0 0 F E T I  4  5  6  7  9  2  0  8  3  CALIBRATED  TO 20,000 FEET  ALT  20  2 0  I0  I 0 I0 I0 20  2 0  TEST  STBY PWR  Figure 8-4.  The flight instruments used for bank control are the attitude, heading, and turn indicators. Figure 6-4. The Bank Instruments.  Pitch-and-bank attitudes can  be determined  simultaneously  on the attitude indicator. Even though the miniature aircraft is not level with the horizo n ba r , pi tch a ttitude c a n be  established by observing the relative  position of the miniature  aircraft and the horizon bar.  [Figure 8-5] 30  small change of bank attitude to center the turn needle and  stop the movement of the heading indicator.  In coordinated flight, the heading indicator gives an indirect  indication of a helicopter’s bank attitude. When a helicopter is  banked, it turns. When the lateral axis of a helicopter is level,  it flies straight. Therefore, in coordinated flight when the  heading indicator shows a constant heading, the helicopter is  level laterally. A deviation from the desir ed heading indicates  a bank in the direction the helicopter is tu rning. A small angle  of bank is indicated by a slow change of h eading; a large angle  of bank is indicated by a rapid change  of heading. If a turn  is noticed, apply opposite cyclic until  the heading indicator  The attitude indicator may show small misrepresentations  of bank attitude during maneuvers that involve turns. This  precession error can be detected immediately by closely  cross-checking the other bank instruments during thes e  maneuvers. Precession is normally noticed when rollin g  out of a turn. If, upon completion of a turn, the miniature aircraft is level and the helicopter is still turning, make  a  Heading Indicator 2 0 2 0 I 0 I 0 I 0 I 0 2 0 2 0 TEST  STBY PWR  0° bank 30° bank 45° bank 60° bank 90° bank Banking scale pointer Banking pointer Horizon Miniature aircraft Figure 8-5.  The banking scale at the top of the attitude indicator indicates varying degrees of bank. In this example, the helicopter is  banked approximately 15° to the right. 8-6