Pratt & Whitney Rzeszów S.A.
MAINTENANCE MANUAL
PZL-10W ENGINE
1992.08.28
73-22-01
Page 11
Export Control Classification: PL/UE 9E999
The limitation level of the compressor turbine rotational speed for the 30 min. OEI rating is to be
adjusted by the N1 5 adjusting screw.
After engaging the valve electromagnet of the OEI parameters, the fuel is supplied under the piston
and enforcing the spring resistance between the piston and the adjusting screw lifts the piston
upwards. The slide exposes the shaped hollow in the controlling slide of the starting and acceleration
corrector enabling further increase of the compressor turbine rotational speed appropriate to the 2.5
min. OEI rating.
The limitation level of the compressor turbine rotational speed tor the 2.5 min. OEI is to be set by the
position of the N21 threaded sleeve.
The limitation settings of the emergency rotational speed limiter of the compressor turbine for the 30
min. and 2.5 min. OEI ratings are higher than corresponding settings in the electronic limiter unit.
The emergency limiter . of the compressor turbine rotational speed operates in the case of the
electronic limiter unit failure.
(12)
Pressure drop valve.
The pressure drop valve consists of the assemblies as follows:
slide pair;
diaphragm assembly;
adjusting assembly.
The fuel pressure ahead of the throttle valve and idle jet is delivered to the spring-diaphragm chamber.
The fuel pressure behind the throttle valve and idle jet is fed to the chamber above the diaphragm. The
pressure drop valve maintains the constant fuel pressure drop at a/m elements, which is adjusted by
the spring tension.
In the case the pressure drop value changes, the flow orifice of the shaped hollow in the slide pair
sleeve will change too, and therefore the fuel capacity in the bypass main changes.
The spring tension and consequently the value of the pressure drop maintained by the valve is to be
adjusted by the L1 adjusting screw.
(13)
Electrohydraulic servo valve.
The electrohydraulic servo valve is a proportional element. The electric signal (electric current
intensity) from the electronic limiter unit is a controlling input signal, and the controlling fuel capacity in
the bypass main is an output parameter.
The valve consists of two stages:
Torque electric motor with two permanent magnets and two coils as well as hydraulic divider;
Slide pair, which constitutes an executive element.
