(f)
If the CSD disconnect does not operate correctly, examine the disconnect circuit. 1) Disconnect the D6 connector from the CSD wire harness. 2) Use an ohmmeter to measure the resistance between the pins
11 and 12 of the wire harness.
a) Make sure that the resistance is less than 100 ohms.
b) If you find more than 100 ohms resistance, repair the
circuit.
3) Examine the continuity between ground and pins 11 and 12 on the D6 connector. a) If you find continuity to ground, repair the circuit.
4) Set the BAT switch on the P5 panel to ON.
5) Remove the lockwire and push the DISCONNECT switch.
6) Look at the dc voltage on pin 11 of the D6 connector.
7) Make sure that the meter shows approximately 28 volts while
the switch is ON and zero while the switch is OFF.
(g) If the disconnect is defective, replace the transmission.
(2)
A disconnect unit failure.
(a) If the disconnect is defective, replace the transmission.
(3)
An internal failure of the CSD.
(a) Remove the magnetic drain plug and look at it.
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(b) If the CSD is damaged, you will find pieces of bright metal on the magnetic plug.
NOTE: Some small particles are satisfactory.
____
(c) Replace the CSD.
(4)
The oil level is lower than is usual in the spline cavity or the CSD.
(a) Fill the spline cavity or the CSD with oil (AMM 12-13-21/301).
(5)
A cold drive (low temperature operation).
NOTE: Start the CSD in cold weather.
____
(a) Open the GCB and operate the CSD/generator in a no-load condition. 1) Operate the CSD in the no-load condition until the oil is
at it's usual temperature.
(6)
The low oil pressure sensor operates incorrectly in a cold
temperature.
(a)
Remove the electrical connector from the low oil pressure sensor.
(b)
Connect a 1000 ohm resistor in series with pin 7 on the pressure sensor.
(c)
Apply 115 volts 400 Hz to the pressure sensor.
(d)
Make sure that you find continuity between pins 7 and 8 on the pressure sensor.
(e)
Connect a milliammeter to the 1000 ohm resistor on pin 7 and to pin 8 on the pressure sensor.
(f)
Make sure that the milliammeter shows 10 milliamps while the pressure is on.
(g)
Make sure that the milliameter shows greater than 40 milliamps, while the pressure is off.
(7)
A voltage regulator failure.
(a)
Install a GCU that has a known good voltage regulator.
(b)
If the circuit operates correctly, replace the defective GCU.
(8)
An open circuit in one or more of the voltage sense wires.
(a)
Operate the applicable generator.
(b)
Make sure you find 115 volts ac between pins A39, A40 and A41 and ground of the GCU.
(c)
If you do not find the 115 V ac, replace the GCU.
(9)
An open circuit in all three of the voltage sense wires.
(a)
Operate the applicable generator.
(b)
Make sure you find 115 volts ac between pins A39, A40 and A41 and ground of the GCU.
(c)
If you do not find the 115 V ac, replace the GCU.
J. Control, Wires and Switches
(1) The APU generator switch or the circuit is defective.
(a) Examine the switch and the wires.
1) Replace the switch or repair the wires.
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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