Pratt & Whitney Rzeszów S.A.
MAINTENANCE MANUAL
PZL-10W ENGINE
1992.08.28
73-22-03
Page 1
Export Control Classification: PL/UE 9E999
ELECTRONIC LIMITER UNIT - DESCRIPTION AND OPERATION
1 .
Description.
A. General information.
(1)
The electronic limiter unit is an electronic analogue system, cooperating with the electric
converters of the physical quantities on the input and with electrohydraulic servo valve
controlling fuel capacity delivered to the engine as well as with the two-state electric executive
assemblies making functions described below, on the output. The electronic limner unit
performs the duties as follows in the fuel control system or the PZL-1 OW engine:
(a)
maintaining permanent power turbine rotational speed on the level chosen by the pilot in
predicted operation range;
(b)
protecting the engine against exceeding the limited values of the power, torque,
compressor turbine rotational speed and gas temperature in the engine;
(c)
control of the air bleed valve behind compressor VI stage;
(d)
emitting the signals after exceeding the set levels of the compressor turbine rotational
speed:
(I)
to the starting system;
(II)
to the engaging system of the OEI ratings;
(III)
to the control system of the running time counters;
(IV)
to the correction disengaging system of change rate of the main rotor pitch when
one engine is run;
(e)
emitting the signal to the fuel delivery closing to the engine at the moment when the
unsafe rotational speed level of the power turbine is exceeded;
(f)
correction of the power turbine rotational speed controller depending on change rate of
the main rotor collective pitch:
(g)
closing control correction of the air bleed from behind compressor VI stage depending
from change rate of the compressor turbine rotational speed
(h)
protection against the engine operation rating decrease below the safe (from the engine
flame-out possibility point of view) level of the minimum rotational speed of the
compressor turbine;
