De Havilland DASH8 100 Series Maintenance Manual page 47

**ON A/C ALL
HIGH PRESSURE COMPRESSOR ROTOR SPEED (NH) INDICATING SYSTEM CALIBRATION
1. Adjustment/Test
Equipment and Materials:
Signal Generator (HP204C or equivalent)
A. High Pressure Compressor Rotor Speed (NH) Indicating System Calibration Check
(1) With dc power on, press test pushbutton on indicator. Check pointer moves
opposite blue dot at 105% Nh and equivalent digital reading. Check on release of
pushbutton indicator returns to original setting.
(2) Open and clip "ENG 1 NH IND" circuit breaker (H5) on 28V dc left circuit breaker
panel (left engine) or "ENG 2 NH IND" circuit breaker (H5) on 28V dc right circuit
breaker panel (right engine) as required.
(3) If engine cowls installed, open right side cowl and disconnect electrical connector
7711−P5 at High Pressure Compressor Speed sensor (refer to Figure 201).
(4) Disconnect electrical connector 9811−P104 located at station X210.00 on left side
of cabin, on relay panel behind avionics rack.
(5) Connect signal generator across pins 1 and 2 of sensor electrical connector
7711−P5.
(6) Close "ENG 1 NH IND" (engine No. 1) circuit breaker or "ENG 2 NH IND (engine
No. 2) circuit breaker, as required.
(7) Adjust signal generator frequency from 0 to 20,000 Hz with not less than 0.5V dc
Peak to Peak (VPP) or greater than 5V Peak to Peak (VPP) to suit calibration check
values in Figure 202.
(8) Record pointer indication for all signal generator inputs (refer to Figure 201) and
confirm indications are within tolerances of Figure 202.
(9) Connect digital voltmeter at receptacle 9811−J104 pins A and B engine (No. 1) or
pins C and D (engine No. 2) and repeat step (7) to obtain digital readings for
indicator and voltage output to Flight Data Recorder (FDR) within limits of Figure
202.
(10) Open circuit breakers (refer to step (2)) and remove signal generator.
(11) Carry out continuity, resistance and insulation check of NH speed sensor (refer to
Engine Maintenance Manual).
(12) Re−install connectors 7711−P5 and 9811−P104.
MASTER
EFFECTIVITY: See Pageblock 77−12−11 page 201
D
S ERIES 100
AIRCRAFT MAINTENANCE MANUAL
CHECK − MAINTENANCE PRACTICES
77−12−11
Dec 20/2004
Page 201