HEADQUARTERS OH-58A, Техническое руководство, Страница: 67 / 292

TM 55-1520-228-10
c. Droop Compensator. A droop compensator
maintains engine rpm (N2) as power demand is in-
creased. The compensator is a direct mechanical
linkage between the collective stick and the speed
selector lever on the N2 governor. Droop is de fi ned
as the speed change in N2 rpm as power is increased
from a no-load condition. Without droop compensation,
instability would develop as engine output is increased,
resulting in N1 speed overshooting or hunting the value
necessary to satisfy the new power condition. If N2
power is allowed to droop, other than momentarily, the
reduction in rotor speed could become critical.
d. Engine Idle Release Control. The engine idle
release is a spring loaded plunger mounted on the
switch box of the pilot collective stick ( fi gure 2-3 and
fi gure 2-4). The plunger prevents the pilot from acciden-
tally retarding the throttle beyond engine idle position.
This acts as a safety feature by preventing inadvertent
engine shutdown. The plunger need not be depressed
when performing an engine start or runup; however,
the plunger must be depressed when accomplishing
an engine shutdown or when it is desired to retard the
power control below the engine idle position.
e. Governor RPM Switch. The GOV INCR/DECR
switch is mounted on the pilot collective stick ( fi gure 2-3
and 2-4). The switch is a three-position momentary type
and is held in the INCR position (FWD) to increase the
power turbine (N2) speed or DECR position (AFT) to de-
crease the power turbine (N2) speed. Regulated power
turbine speed may be adjusted in fl ight through the op-
erating range by movement of the switch as required.
f. Gas Producer Fuel Control. The gas producer
fuel control has a bypass valve, metering valve, ac-
celeration bellows, governing and enrichment bellows,
manually operated cutoff valve, maximum pressure
relief valve, and a torque tube seal and lever assembly.
A maximum pressure relief valve is incorporated to
protect the system from excessive fuel pressure.
g. Power Turbine Governor. The power turbine
speed is scheduled by the power turbine governor
lever and the power turbine speed scheduling cam.
The cam sets a governor spring load which opposes
a speed-weight output. Overspeed protection of the
power turbine governor becomes effective at approxi-
mately 108% N2. This governing action will result in a
pulsating increase/decrease of engine power.
h. Deleted.
i. Fuel Pump and Filter Assembly. The fuel pump
and fi lter assembly incorporates a single gear-type
pumping element, a low pressure barrier fi lter, a fi lter
bypass valve, and a bypass pressure regulating valve.
Fuel enters the engine fuel system at the inlet port of the
pump and passes through the low pressure fi lter before
entering the gear element. The fi lter bypass valve
allows fuel to bypass the fi lter element if it becomes
clogged. The bypass return fl ow from the fuel control is
passed back to the inlet of the gear element through a
pressure regulating valve which maintains the bypass
fl ow pressure above inlet pressure.
j. Deleted.
k. Fuel Nozzle. The fuel nozzle is a single-entry
dual ori fi ce type unit which contains an integral valve
for dividing primary and secondary fl ow.
l. Deleted.
Change 14 2-23