TASK 32-61-00-765-196
 3.  Inductance and Resistance Test of the Proximity Sensors_______________________________________________________
 A. General
 (1)
This procedure does these tasks:

 (a)
Test the resistance of each sensor.

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 (b)  
Tests the inductance of each sensor and compares it to a known tolerance for the target far and the target near position.

 (c)  
This task checks the resistance and inductance of the landing gear sensors. For sensors which have high resistance values or bad inductance values, refer to FIM 32-09-03/101 to decide to adjust the sensor or replace the sensor.

 (2)  
This test requires the airplane to be on jacks to swing the landing gear. This allows all landing gear sensors to be tested in the target far and target near conditions.

 B.
Reference

 (1)  
AMM 07-11-01/201, Jack the airplane

 (2)  
AMM 29-11-00/201 , Pressurize the Hydraulic System

 (3)  
FIM 32-09-03/101, Proximity Switch System

 C.
Equipment

 (1)  
BK Precision model 878 or 875B Inductance meter or equivalent, 1000Hz excitation frequency.

 D.
Access

 (1)  
Location Zones
 119 Main Equipment Center (LH, RH)

 E.
Prepare for the test

 S 025-197
 (1)  
Do this task: Remove the PSEU, AMM 32-09-04/401

 S 765-199

 (2)  
Measure the resistance at the pins on the E3 rack for each main and nose gear sensor.

 NOTE: Refer to WDM 32-61-XX for the position indication sensors.
____ Refer to WDM 32-09-XX for the air/ground sensors.
 ú (a)  If the resistance is greater than 20 ohms, refer to FIM 32-09-03/101 to correct the problem.
 S 765-201
 (3)  Measure the inductance at the pins on the PSEU connector on the E3 rack for each main and nose gear sensor.
 NOTE: If the excitation frequency on the inductance meter is
____ selectable, then you should select a frequency of 1000 Hertz.
 (a)  
Record the inductance value and target position (near or far) for comparison to the inductance values listed in the steps below.

 (b)  
Measure the sensor inductances with the gear in both the down and up positions. Refer to AMM 07-11-01/201 to jack the airplane to permit gear retraction.

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OVERHEAD CIRCUIT
E3 RACK

Proximity Switch System - Component Location
Figure 508

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 S 045-226
 WARNING: DO THE DEACTIVATION PROCEDURE FOR THE SPOILERS OR MOVE ALL
_______ PERSONS AND EQUIPMENT AWAY FROM THE SPOILERS. THE SPOILERS CAN MOVE QUICKLY AND CAUSE INJURIES TO PERSONS AND DAMAGE TO EQUIPMENT.
 (4)
Do the deactivation procedure for the spoilers (AMM 27-61-00/201).

 S 865-204

 (5)  
Move all three landing gears to the up position.

 S 765-205

 (6)  
Measure the inductance of all landing gear sensors. Record the target positions of all sensors as target near or target far.

 (a)  
If the inductance for a sensor in the target near position is below 5.2 millihenries or more than 6.5 millihenries, refer to FIM 32-09-03/101 to correct the problem.

 NOTE: The left and right gear down sensor inductance in the
____ near state may be lower than 5.2 millihenries. If there are no related EICAS messages or system anomalies, then readings between 5 and 5.2 millihenries are acceptable.
 (b)  
If the sensor inductance for the target far state is greater than 5.0 millihenries or less than 4.7 millihenries, refer to FIM 32-09-03/101 to correct the problem.

 F.
Put the airplane back to the normal condition.

 S 585-211
 (1)  
Lower the airplane from the jacks (AMM 07-11-01/201), if it is no longer necessary.

 (2)  
Install the PSEU (AMM 32-09-04/401).

 S 845-208

 (3)  
Put the safety-sensitive systems back to their initial conditions (AMM 32-09-02/201).

 (4)
　
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