Message Name:

LH OR RH PRIMARY NAV LIGHT DOES NOT ILLUMINATE

Left Hand (LH) or Right Hand (RH) Primary Navigation Light does not illuminate.

• Left Primary Wing Navigation Light Bulb
• Right Primary Wing Navigation Light Bulb
• Left Primary Wing Navigation Light (DS8)
• Right Primary Wing Navigation Light (DS10)
• Navigation Control and Indication Unit (A126)
• Thermal Switch (S42)
• Thermal Switch (S43)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

1. Set NAV switch to ON.

   1. If all the navigation lights do not come on, perform the troubleshooting ALL NAV LIGHTS DO NOT ILLUMINATE and continue with next step.
   2. If any one of the navigation lights do not come on, continue with next step.

2. Access Navigation Light Status data page on CAIMS and perform:

   • Select System Diagnostics
   • Select ATA 33
   • Select the Navigation Light Status
     
     NOTE: Ensure that the power of the NAV Light is selected ON for a minimum of 10 minutes prior to reading the values displayed on the CAIMS data page.

3. Check the status of Primary Navigation Light as follows: Is “TRUE” displayed next to Primary light in data page?

   1. If NO, go to step 7.
   2. If YES, continue with next step.

4. Replace the NAV light bulb.

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.

5. Perform a continuity check of the thermal switch (S42 or S43).

   1. If there is no continuity, replace the defective thermal switch and do close out.
   2. If there is continuity, continue with next step.

6. Perform a continuity check as follows:
   RH Primary:

   From	To	Result
   A126P1-P	A126P1-F

   LH Primary:

   From	To	Result
   A126P1-P	A126P1-B

   1. If there is no continuity, go to step 11.
   2. If there is continuity, continue with next step.

7. Check the status of Primary Navigation Light as follows: If 'False' is displayed next to "Primary light" on the data page?

   • Confirm that SB 700-33-023 or 700-1A11-33-008 is NOT incorporated on the aircraft
   • Ensure that the power of the Navigation light is selected ON for a minimum of 10 minutes prior to reading the values displayed on the CAIMS data page
   • Confirm that the Failure Indication Box is connected properly
   • If all good, continue with next step

8. Perform a continuity check as follows:
   RH Primary:

   From	To	Result
   A126P1-P	A126P1-F

   LH Primary:

   From	To	Result
   A126P1-P	A126P1-B

   1. If there is no continuity, go to step 11.
   2. If there is continuity, continue with next step.

9. Ensure that the NAV light bulb is secured into place.

   1. If damages are found, repair or replace as required and do close out.
   2. If damages are not found, continue with next step.

10. Perform a continuity check as follows:
    RH Primary:

    From	To	Result
    A126P1-F	DS10-1
    A126P1-P	GS218

    LH Primary:

    From	To	Result
    A126P1-B	DS8-1
    A126P1-P	GS218

    1. If there is no continuity, repair defective wiring as required and do close out.
    2. If there is continuity, continue with next step.

11. Replace the Failure Indicator Box.
12. Do close out.