When operating over dense foliage, the
radar altimeters will indicate the altitude to
the tops of the trees. When operating over
sparse foliage, the altimeters may indicate
the altitude between the ground and about
half the average tree height, depending on
ground speed. When external cargo is car-
ried, the radar altimeter may occasionally
indicate the distance between the bottom
of the helicopter and the load.
Set RAD ALT dimming control to desired
digital display light level.
Set HI and LO indexes as desired. If the
helicopter exceeds one of these indexes, an aural warn-
ing message will be heard at full volume initially, but the
volume level can be decreased by one-half (1/2) by
pressing the PUSH-TO-TEST once or inhibited by press-
ing PUSH-TO-TEST a second time. If HI or LO indexes
are not desired, set the LO index at 0 feet or the HI index
above 1,500 feet.
2-14-15. VERTICAL SPEED Indicator.
Two VERTICAL SPEED indicators are in the instrument
panel (fig. 2-1-7 and 2-1-9). They indicate the rate of
climb based on the rate of change of atmospheric pres-
sure. The indicator is a direct-reading pressure instru-
ment requiring no electrical power for operation.
2-14-16. Attitude Indicator.
Two attitude indicators are on the instrument panel (fig.
2-1-7 and 2-1-9). The attitude indicators have been spe-
cifically tailored for the flight characteristics of a helicop-
ter by the inclusion of an electrical trim capability in the
roll axis in addition to the standard pitch trim. Normal
flight attitudes of helicopters, defined by fixed amounts of
roll as well as pitch, are easily trimmed into this indicator,
and optimum operation of the helicopter in an attitude
such as hover is facilitated. Degrees of pitch and roll are
indicated by movement of a universally mounted sphere
painted optical black and light gray to symbolize earth
and sky, with a horizon line separating the two colores.
To adjust the miniature aircraft in relation to pitch, use the
lower knob. The pitch adjustment range is about 5_ nose
up and 10_ nose down minimum. To compensate attitude
in the roll axis, use the upper knob. The roll adjustment
range is about 8_minimum in either direction.
Rapid rotation of the pitch and roll trim knobs
on the attitude indicator may cause abrupt
pitch and roll attitude changes with AFCS on.
The indicator incorporates integral lighting. The pilot and
copilot attitude indicators should erect within 90 seconds
after electrical power is applied. Power to operate the
attitude indicator gyros is supplied by the No. 1 and No.
2 AC bus through the NAV PILOT VGI and NAV COPLT
VGI circuit breakers on the No. 1 and No.2 PDP.
2-14-17. Pilot and Copilot Attitude Indicator (VGI)
A VGI switch is on the instrument panel below each atti-
tude indicator (fig. 2-1-7 and 2-1-9). The switch is labeled
NORM and EMER. When the switch is at NORM, each
attitude indicator operates from a separate gyro. If either
the pilot or the copilot gyro fails, signaled by the OFF flag
on the indicator, manual switching to the remaining gyro
is accomplished by placing the respective VGI switch to
EMER. The switching of the gyros from NORM to EMER
operation is accomplished by a gyro transfer relay. Fail-
ure of the gyro will also result in failure of the associated
AFCS. Power is supplied by the No. 2 DC bus through the
NAV CONT VGI circuit breaker on the No. 2 PDP.
2-14-18. Turn and Slip Indicator (4-Minute Type).
Each turn and slip indicator (fig. 2-1-7 and 2-1-9) is con-
trolled by an electrically actuated gyro. The instrument
has a pointer (turn indicator) and a ball (slip indicator).
Power to operate the gyros is supplied by the DC essen-
tial bust through the NAV TURN & SLIP circuit breakers
on the No. 1 and No. 2 PDP.
2-14-19. Magnetic Compass.
The magnetic compass is mounted on the top of the
center instrument panel glareshield (fig. 2-1-3). It is a
direct reading instrument requiring no electrical power. It
consists of compass card mounted on a magnetic ele-
ment in a liquid-filled bowl.
2-14-20. Free Air Temperature Gauge.
The free air temperature gauge is on the exterior of the
pilots eyebrow window (fig. 2-1-3). The unit is calibrated
in degrees from -70 to + 50_C.