
Pratt & Whitney Rzeszów S.A.
MAINTENANCE MANUAL
PZL-10W ENGINE
1992.08.28
77-02-00
Page 601
Export Control Classification: PL/UE 9E999
GAS TE MPERA TURE MEASURE MENT AND LI MI TA TION S YS TE M - INSP ECTION A ND CHE CK
1.
Electric resistance measurement of the thermocouple circuit and insulation resistance in relation to the engine mass.
NOTES:
1.
Use any of ohmmeters oí the class no worse than 1.5 to measure the electric resistance of the
thermocouple circuits.
2.
Use any of megaohmmeters of measurement voltage of 100V and of the class no worse than 2.b to
measure the insulation resistance of the thermocouple circuits.
A.
Disconnect the terminals of the electric leads of the helicopter system from both inserts on the thermocouple
board, leaving the terminals with the leads of the thermocouple collector connected to the inserts.
B.
Measure the electric resistance of the thermocouple circuits with the ohmmeter connecting the ohmmeter
measurement leads to the M4 and M5 threaded studs on the insert. Make two measurements on each insert
changing the connection polarity of the ohmmeter leads and calculating the resistance value as arithmetic
mean value from two measurements.
C.
Repeat the electric resistance measurement for the second thermocouple circuit connecting the leads and
measuring the resistance as per item B but on the second insert.
D.
The value of the electric resistance of the thermocouple circuit measured in accordance with items B and C
shall be in the range of 0.39 ÷0.45 Ω,
E.
Measure the insulation resistance of the thermocouple circuit in relation to the engine mass with the
megaohmmeter, connecting in succession one lead of the megaohmmeter to the M4 threaded stud and next
to the M5 stud and the second lead to the engine mass.
F.
Repeat the measurement of the insulation resistance of the second thermocouple circuit, connecting the leads
and measuring the resistance as per item E but on the second insert.
G.
The value of the insulation resistance measured in accordance with item E and F shall be no smaller than 5
kΩ.
H.
Connect the terminals of the helicopter system electric leads disconnected according to item A to both inserts
on the thermocouple board.
NOTE:
The electric parameters of the helicopter part together with the engine part of the measurement and
limitation system of the gas temperature behind compressor turbine should conform to the
requirements of present used receivers to which they are connected.
For the gas temperature indicator of the TCT-2 type, the resistance of the thermocouple circuit
connected to it shall be in the range from 8.94 Ω to 9.06 Ω, while for the ALAE-2 electronic limiter
unit - from 10 Ω to 12 Ω. The test procedure and the values of tested parameters are presented in
the Helicopter Maintenance Manual.