Overview

This article walks you though how to troubleshoot an LED PAPI. You can also view a more guided flow style walkthrough by using the link below. Select L880/L881 from the product guides dropdown box.

Guided Product Troubleshooting

Identify the Symptoms

• Record each symptom observed

  • Are some or all of the light heads off?
  • Are there any errors being displayed on any of the boxes?
  • Is the light dim (noticeably weaker than normal), flickering/intermittent, or going on and off randomly?
  • Is the problem limited to day or night mode?
  • Do you see any obvious damage to any of the electronics?
  • Are any of light head displays off even when energized?
  • Was there any environmental factors?

Scroll down and stop when you see the heading that describes your symptoms.

One or more light head(s) are completely off and the display doesn't turn on when the system is energized

Remove the side panel covering the power conditioning board, and inspect the input power components for damage and functionality. Repeat this for each affected head and record your findings.

Voltage Based System

If you have determined that the input power is the problem:

• Test the power supply for 48V output
• Test the Power Conditioning Board
  Reference: Replacing the Power Conditioning Board 
  
  

Current Based System

If you have determined that the input power is the problem:

• In a current-based system, test the input power at the LVCV2 power supply by measuring DC voltage on the two outside pins.
  Reference: Testing an LVCV2 Power Supply
• If you do not have the 48V required
• Test the Bridge Rectifier
• Verify Isolation Transformer Output Current / Fixture Input Current
• Test the Power Conditioning Board
  Reference: Replacing the Power Conditioning Board 

 

 

The lights are dim (noticeably weaker than normal), flickering/intermittent, or going on and off randomly.

• Try the above steps in addition to a
  
  • Perform a megger test and record the results 
    Reference Article : Performing Megger Testing for Airfield Lighting Systems 
  • Test the isolation transformer
    Reference Article : Verify Input Current (Isolation Transformer Test)

 

The display on the side of each light head will give you a clear indication of what is happening

Review any errors being displayed with the table below

 

Error	Cause	Solution
Tilt Fail	The light head has deviated from the saved glide slope Failed control and tilt board	Review the angle required with the current angle and make an adjustment if needed Level and Tilt the Light Head (Set the Glide Slope) Replace the Control and Tilt Board Board
LED Fail	Check the harness running from the LED board and the control board Number of failed LEDs exceeds the number allowable per FAA spec Power Conditioning Board Failure Absence of DC to DC	Replace the harness Replace the LED board Replacing the Power Conditioning Board  Install a DC to DC
Phot Fail	Loose harness connection  Failed Photosensor Board	Replace the harness Replace Top Assembly
Comm 485 Lost	Incorrect Dipswitch Configuration (SW3) Failed RS 485 Board Loose connection in LHA	Correct the Dipswitch Configuration Check connections in LHA and tighten  Replace the RS485 Communications Board
Heat Fail	Failed thermostat Failed heater	Replace the Thermostat Board Replace heated lens assembly

 

 

Airport Lighting Company | L-880(L), L-881(L) Precision Approach Path Indicator Lights (PAPI)