A O M  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  2 0 2 0 I 0 I 0 I 0  I 0 2 0 2 0 TEST  STBY PWR  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  Primary bank initially Supporting pitch Primary bank as turn is established Supporting pitch Primary pitch Remains constant Primary power Figure 8-14.  Flight instrument indications in a standard-rate turn to the left. Prior to  performing timed turns,  the turn coordinator should  be calibrated to determine the  accuracy of its indications.  To do  this, establish a standard  rate turn by referring to the  turn-and-slip indicator. Then, as the sweep second hand of  the clock passes a cardinal point (12, 3, 6, or 9), check the  heading on the heading indicator. While holding the indicated  rate of turn constant, note the heading changes at 10-second  intervals. If the helicopter turns more or less than 30° in  that interval, a smaller or larger deflection of the needle is  necessary to produce a standard rate turn. After the turn- and-slip indicator has been  calibrated during turns in each  direction, note the corrected  deflections, if any, and apply  them during all timed turns.  Use the same cross-check and contr ol technique in making  timed turns that is used to make tu rns to a predetermined  heading, but substitute the clock fo r the heading indicator.  The needle of the turn-and-slip i ndicator is primary for  bank control, the altimeter is primar y for pitch control, and  the airspeed indicator is primary fo r power control. Begin  the roll-in when the clock’s second  hand passes a cardinal  point; hold the turn at the calibrated  standard rate indication  or half-standard rate for small ch anges in heading; then  begin the roll-out when the compu ted number of seconds  has elapsed. If the roll-in and roll-ou t rates are the same, the  time taken during entry and recovery need not be considered  in the time computation.  Pitch and power control  techniques are the same as those  used during airspeed cha nges in straight-and-level flight.  As discussed previously,  the angle of bank necessary for a  given rate of turn is  proportional to the true airspeed. Since  the turns are executed at  standard rate, the angle of bank  must be varied in direct  proportion to the airspeed change in  order to maintain a constant rate of turn. During a reduction  of airspeed, decrease the an gle of bank and increase the pitch  attitude to maintain altitude and a standard rate turn.  Changing airspeed in turns is an effective maneuver for  increasing proficiency in all three basic instrument skills.  Since the maneuver involves simultaneous changes in all  components of control, pr oper execution requires a rapid  cross-check and  interpretation, as well as smooth control.  Proficiency in the maneuve r also contributes to confidence in  the instruments during  attitude and power changes involved  in more complex maneuvers.  If practicing timed turns  with a full instrumen t pane l,  check the heading indicator for the accuracy of  the turns. If executing turns without  the heading indicator, use t h e  magnetic compass at the com pletion of the turn to check turn  accuracy, taking compass deviation errors into consideration.  Change of Airspeed in Turns 8-14