MD Helicopters 369-500, Инструкция по техническому обслуживанию

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CSP-HMI-3
MD Helicopters, Inc
.
MAINTENANCE MANUAL
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Neither this document nor any part hereof may be reproduced or transferred to
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purpose except as specifically authorized in writing by MD Helicopters, Inc.
Copyright
©
1999 − 2016 by MD Helicopters, Inc.
INSTRUMENTS
DESCRIPTION AND OPERATION
1. Instrument Description
Three basic types of instrument indicating
systems are installed in the helicopter.
(1). The first group includes indicators that
are actuated by other than an electrical
power input: these are the airspeed
indicator, altimeter, outside air temper­
ature indicator, engine torque gauge,
engine oil pressure gauge and magnetic
compass.
(2). The second group of indicators are
interconnected with electrical sending
units that self-generate the electrical
power source necessary for indicator
operation once they are mechanically or
thermally actuated; indicators in this
group are the N
1
and N
2
rotor tachome­
ter indicators and TOT indicators.
(3). The third group includes those indica­
tors and sending units that rely on
electrical power input from the helicop­
ter electrical system for functional
capability; such indicators include the
caution and warning lights and the
instrument cluster 3-pack.
NOTE:
For specific helicopter instrument limit
markings, refer to applicable PFM (Ref.
Table 201, Sec. 01-00).
A. Altimeter Description
The altimeter indicates altitude in feet above
sea level from 0 to 20,000 feet. A small scale
on the instrument face is rotated by a knob at
the lower left for adjustment to ambient
barometric pressure. After this adjustment is
accomplished, the altimeter indicates actual
height of helicopter in feet above sea level.
B. Airspeed Indicator Description
The airspeed indicator is a pressure-sensitive
unit actuated by the differential between
impact and static air pressures. The pitot tube
and airspeed indicator function in forward
flight only; speed of rearward or sideward
movement is not indicated.
C. Three − Pack Description (369D)
The instrument cluster three-pack is a single
unit instrument assembly with three indica­
tors that show generator output in amperes,
engine oil temperature in degrees centigrade
and operating fuel weight in pounds.
NOTE:
If there is an indicator malfunction,
complete instrument cluster should be re­
placed.
(1). The engine oil temperature sender and
fuel quantity sender function as
variable-resistance legs of their
associated instrument bridge circuit. As
temperature changes or float arm
position changes, sender resistance is
changed causing an imbalance in
current flow through indicator windings
to move the applicable indicator
pointer.
(2). Ammeter pointer movement results
from and is proportional to the helicop­
ter main power output.
(3). Early Model (AC) Instrument Clusters
(369D294579, 369D26415):
(a). (Ref. Figure 501) Early model
instrument clusters operate on a
nominal 14.5 Vdc. Helicopter electri­
cal 28 Vdc power is reduced
by voltage-dropping resistor R1,
located on terminal board TB8, to
meet the 14.5 Vdc requirement.
Except for the ammeter, external
fixed-value resistors are mounted
across the input terminals of each
instrument. These resistors are
furnished as part of the instrument.
Ammeter current flows through
resistor R500.
(b). R/H command T-Panels only:
Voltage dropping resistor R112, used
to 28 Vdc input voltage for
internal panel lamps, is mounted on
the back of the early instrument
cluster assembly.