Pratt & Whitney Rzeszów S.A.
MAINTENANCE MANUAL
PZL-10W ENGINE
1992.08.28
73-22-01
Page 13
Export Control Classification: PL/UE 9E999
The fuel pressure proportional to the observed rotational speed of the compressor turbine is delivered to
the spring-diaphragm chamber. The slide moves to the right and opens the shaped hollow in the sleeve
when the pressure decreases.
The controlling fuel in the bypass main is passed to the low pressure side. As a result the controlling fuel
capacity will increase up to such value, that the rotational speed drop of the compressor turbine ceases
preventing the engine shutdown.
The spring tension and consequently the value of the minimum observed rotational speed of the
compressor turbine is to be set by the Z5 screw.
The compressor turbine rotational speed drop may occur in the case of prolonged closing of the controller
flow orifice governing the controlling fuel capacity in the bypass main.
The minimum observed rotational speed valve is doubling limiter of the minimum corrected rotational
speed of the compressor turbine mounted in the electronic limiter unit.
The minimum observed rotational speed acts in the case when the bypass main is completely closed by
the slide pair of the power turbine rotational speed limiter. At that time, the switching valve opens and
enables the flow through the minimum observed rotational speed valve.
NOTE:
The complete closing of the bypass main occurs in the case of prolonged power turbine
rotational speed exceeding at the helicopter main rotor pitch decrease. The power turbine
rotational speed limiter steers then to the decrease of the engine operation rating and
decreases the bypass flow orifice up to its full closing.
(16)
Deceleration jet.
The deceleration jet is parallelly connected to the controlling fuel main. It enables the fuel flow from the
bypass main to the low pressure side. The fuel flow in the metered fuel main drops up to zero during the
deceleration, when the flow orifices of the pressure drop valve and electrohydraulic servo valve are
closed. The deceleration jet prevents the engine shutdown maintaining the fuel capacity in the metered
fuel main, necessary for the stable combustion chamber operation during the deceleration.
(17)
Drain valve.
The drain valve consists of the assemblies as follows
slide pair;
diaphragm assembly;
adjusting assembly.