REFER TO INTERNAL DOCUMENT
REFER TO INTERNAL DOCUMENT
Range marks are a green arc 0 to 90%, a yellow arc 90 to 105%, a dashed red limit
(radial) at 105% torque and solid red limit mark (radial) at 90% torque.
On aircraft with SOO 8152 incorporated, range marks are a green arc 0 to 97.5%, a
yellow arc 97.5 to 112.5%, a dashed red limit (radial) at 112.5% torque and solid red limit
mark (radial) at 97.5% torque.
The digital display is a 4−digit liquid crystal display (LCD) type. Pre mod 8−1/1101
aircraft incorporate a heater associated with LCD operation, one in each indicator
powered from the 28 V dc secondary buses, engine No. 1 indicator heater from the left
bus and engine No. 2 indicator heater from the right bus (refer to ENGINE INDICATING
− GENERAL).
A 0 to 5 V dc signal proportional to 0 to 100% torque is relayed to the flight data recorder
(refer to Chapter 31).
An overtorque switch located in each indicator, is connected in series with overtorque
relay power supply circuits for the corresponding engine, relay 7712−K5 engine No. 1
and 7712−K4 engine No. 2.
In the event of engine overtorque, a circuit to ground is completed by the overtorque
switch in the indicator. The overtorque and Np governing cancel relay energizes to
connect the corresponding ECU ’cancel Np gov’ discrete to ’discrete return’ to cancel Np
underspeed governing. The power uptrim relay of the opposite engine fuel control
system energizes (in conjunction with autofeather circuits) to remove 28V dc power from
the associated ECU ’opp. engine uptrim’ discrete, which initiates engine uptrim.
A press−to−test pushbutton on the front of the indicator can be used to verify operation
of indicator internal circuits. Pressing the test button, with power applied to the indicating
system causes the pointer to move to a position opposite a blue dot at 105% torque, with
an equivalent reading on the digital display and initiates operation of the overtorque
switch.
Overtorque switch operation is verified in conjunction with autofeather control circuits.
With autofeather selected (refer to Chapter 61) a ground is established for the
associated power uptrim relay for each engine. Pressing the press−to−test button on the
front of the indicator results in dial indications, with overtorque switch actuation verified
by a ‘power uptrim’ light on the engine instrument panel which turns on.
C.
Torque Indicators − Functional Test
(1) Make sure 28V dc power on aircraft buses.
(2) On left dc circuit breaker panel, make sure the following circuit breakers are closed:
ENG 1 TORQUE IND (K6)
ENG 1 TORQUE COND (L6)
(3) On right dc circuit breaker panel, make sure the following circuit breakers are
closed:
ENG 2 TORQUE IND (J5)
ENG 2 TORQUE COND (K5)
(4) Make sure the power levers are at FLT IDLE positions. At the engine instrument
panel, push the AUTOFEATHER select switch/light (SELECT light on). Press and
hold press−to−test switch on left indicator. Check that indicator pointer goes to blue
dot at 105%, rim pointer (’bug’) goes to blue dot at 85% (Pre Mod 8/1292), digital
display shows 105%.
D
SERIES 100
AIRCRAFT MAINTENANCE MANUAL
MASTER
EFFECTIVITY: See Pageblock 77−10−00 page 1
77−10−00
Page 2
Jun 20/2005