
Pratt & Whitney Rzeszów S.A.
MAINTENANCE MANUAL
PZL-10W ENGINE
73-02-00
1992.08.28
Page6
Export Control Classification: PL/UE 9E999
The power turbine rotational speed limiter operates for the governor, that does not allow the power turbine (helicopter main rotor)
rotational speed to increase above the rotational speed resulting from its characteristic. In the case the power turbine rotational
speed increase up to the value maintained by the power turbine rotational speed limiter in accordance to its
characteristic (after shifting), it begins to correct the fuel capacity delivered to the engine combustion chamber, taking over the fuel
capacity control in the bypass main.
In the EMERGENCY OPERATION mode, the engine operation rating may be also controlled through the power turbine rotational
speed limiter intervention only. For this purpose the CL should be set in upper position of the EMERGENCY OPERATION range
(i.e. 90°) and the power turbine rotational speed should be increased to the value maintained by the power turbine rotational speed
limiter in accordance to its characteristic (after shifting). The flow orifice of the power turbine rotational speed limiter slide pair is in
this case the control orifice in the bypass main. It will meter the fuel capacity delivered to the engine combustion chamber according
to the helicopter main rotor (and tail rotor) power demand maintaining the constant rotational speed of the helicopter main rotor. The
engine operational rating will be set automatically in respect to the helicopter main and tail rotors pitch.
NOTE:
The engine operation control through the power turbine rotational speed limiter intervention may be used at the one
engine running (second inoperative).
At the both engine running, this control mean does not assure the
both engines power synchronization - big difference
of the torques and compressor turbine rotational speed may occur. Therefore this
mean at the both engines running is
not recommended.
No engine output shaft torque automatic synchronization and no engine output shaft torque limitation when the maximum allowable
value will be achieved at the operation in the EMERGENCY OPERATION mode. The remaining limitations of the engine operation
parameters do not act too. The electronic limiter unit assures only the control of the air bleed from behind compressor VI stage and
engine shutdown in the case of the power turbine overspeed.
The hydromechanic limiters of the engine operation parameters act in the ordinary course.
The position of the control lever (CL) on the fuel metering pump scale:
α
CL
=
0 ÷ 10°
engine shutdown
α
CL
=
25 ÷ 40°
GROUND IDLE (Gl)
α
CL
=
50 ÷ 60°
engine starting
α
CL
=
40 ÷ 90°
MANUAL CONTROL
α
CL
=
90 ÷ 100°
AUTOMATIC OPERATION
α
CL
=
11
0
÷ 120
̊
˚
disengaging of the electrohydraulic
servo valve
α
CL
=
40 ÷ 90°
EMERGENCY OPERATION