Service difficulty report · Proximity Switch · Boeing 7379

Difficulty date
April 5, 2026
Submitted
April 7, 2026
Operation
Air carrier
Aircraft
N17421
Make and model
Boeing 7379
Aircraft serial
67744
Aircraft time
813 hours, 280 cycles
Part
Proximity Switch
Part number
285A1600102
Part serial
F10858
Condition
Faulted
Location
Zone 200
Part time
812 hours, 279 cycles
Stage of operation
TO
How discovered
O
Nature of condition
N
Precautionary procedure
C

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

LEFT FWD AND AFT OVERWING EXIT LIGHT ON, ON PWR ADV ON TO FADED. DIFFICULTY EXTRACTING WIRES FROM CONNECTOR WITH WIRES PULLERS. R & R PROXIMITY SWITCH ELECTRONICS UNIT IAW AMM 32-09-10-400-801. LRU REPLACEMENT TEST STILL SHOW FAIL. DURING REMOVAL ONE BOLT/NUTPLATE WAS DAMAGED. PERFORMED WIRING TROUBLESHOOTING IAW SSM 52-71-13-102. INITIAL VOLTAGE CHECK OF PSEU PLUG D10986 PIN 40 SHOWED NO VOLTAGE. CONTINUITY CHECK FROM PIN 40 TO X2 OF RELAY R742 SHOWED GOOD CONTINUITY. PERFORMED VOLTAGE CHECK AT X1 OF RELAY SOCKET & VOLTAGE WAS GOOD. REINSTALLED RELAY R742 & VOLTAGE WAS NOW GOOD AT PSEU PIN 40. REINSTALLED CONNECTORSS ON PSEU & PERFORMED POWER ON CHECK OF PSEU IAW AMM 32-09-10-710-801 LRU REPLACEMENT. SYSTEM TEST PASSED. REPLACED RELAY IAW AWM 73-22-31. DURING OPS TEST OF PSEU FOR R737 CHANGE TEST FAILED WITH MX MSG 52-76017. MX PERFORMED POWER ON CHECK OF PSEU IAW AMM 32-09-10, LIGHT INDICATION ON IN THE COCKPIT.

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