Pratt & Whitney Rzeszów S.A.
MAINTENANCE MANUAL
PZL-10W ENGINE
73-02-00
1992.08.28
Page 4
Export Control Classification: PL/UE 9E999
Electronic limiter unit converts the inlet signals fro m engine operation parameters pick-ups and ambient
temperature to the electr ic signal that controls the metered fuel capacity delivered to the combustion
chamber, the electric signal that activate the valve controlling the air bleed from behind compressor VI
stage and the signals used for engine starting automatic control and to engage the OEI ratings.
In addition the independent emergency power turbi ne speed limiter incorporated In the electronic limiter
unit causes the engine shutdown in the case of the powe r turbine (helicopter main rotor) overspeed.
W ARNING:
I T IS PROHIBI TE D TO SW ITCH- OF F THE ELECTRONIC LI MITE R UNI T SUP PL Y I N THE
CASE OF THE TRANSI TI ON TO THE E MERGE NCY OP ERA TI ON CONTROL .
SW ITCHI NG-OFF THE S UPPL Y OF THE EL ECTRONIC LI MI TER UNI T CAUSE S THE
SW ITCHI NG-OFF THE P OW ER TURBINE SPE ED E ME RGENCY LI MI TA TI ON S YS TE M.
In the case of one engine inoperative, the electronic limiter unit of the operating engine automatically
increases the limited levels of compressor turbi ne rotational speed and compressor turbine out let
temperature and torque.
It enables to get required for safe flight increased powe r rating (30 min. OE I) or after pushing the OEI
button the highest power level (2.5 min. OEI).
The fuel metering pump beside the electronic limiter unit is the main con trol unit in the fuel contr ol
system and controls the metered and starting fuel capacity delivered to the engine combustion chamber
during all engine operation states. It depends on the position of the control lever (CLL compressor
turbine rotational speed a nd air pressure behind co mpressor. The pump is al so the e xecuti ve element of
the electronic limiter unit and powe r turbine speed limiter.
The po we r turbine speed limiter participates in controlling the metered tuel capacity only during t he
manual adjustment of the engine operation ratings - E MERGENCY OPE RA TION. It secures the engine
against the power tu rbine (helicopter main rotor) r otational speed increase above the allo wed operati on
range at that time.
During the automatic adju stment of the engine oper ation ratings - A UTOMA TI C OPERA TION, it p rovide s
the next (last before the engine shutdown) power turbine protection against the damage because the
overspeed appearance.
Remaining assemblies do not participate in the fuel capacity control.
The fuel control system may operate in the engine operation automatic control mode or the engine
operation manual operation control or the EMERGENCY OPE RA TI ON mode.
